This example shows how to Load, Add, Subtract, and Intersect selections between overlapping layers just with quick thumbnail clicks.

Load Pixels to Selections

In “Layer 2″ Command-click to load a fill as a selection. Any pixel which is not transparent in “Layer 2″ will be loaded as a selection. This is not the same as copying the layer, only its outline. The green fill shows the selected region although you will get only the surrounding Marquee. Let’s call this state (with “Layer 2″ selected) the initial state.

Addition

With the “Layer 2″ loaded as a selection, Command + Shift-click on “Layer 1″ to add it to the selection. Now non-transparent pixels of both “Layer 1″ and “Layer 2″ are combined as the new selection. Notice the small plus sign in the Command-Click box.

Subtraction

Revert to the initial state and Command + Alt-click on “Layer 1.” This will subtract any overlapping pixel of “Layer 1″ from the current selection of “Layer 2.” Notice the minus sign.

Intersection

Revert to initial state and Command + Alt + Shift-click on “Layer 1″ to keep only the overlapping pixels as a selection. Notice the X sign. If the layers are not overlapping this action will deselect all.

Garbage Masks

Garbage Masks are created to roughly isolate the ‘region of interest’ from rest of the image. Further trimming is carried out inside the Garbage Mask with precision.

Vector and Raster Selections

Draw an outline around the region of interest in the image with any of the Lasso Tools and double-click to complete the selection. A Garbage Mask needs to be saved for further refining, which can be done both as a Layer or Vector Mask. We must choose it depending on complexity of the outline and how we are planning to trim it later on. With the Lasso selection click Add Layer Mask to save it as a Layer Mask.

Alternatively, we can also save the selection as a Vector Mask which can be later refined by working on the shape spline that defines its outline. With the Lasso selection still intact (2), go to the Paths tab (3b) and click Make Working Path from the Selection button at the bottom. This will save the selection outline as a Shape Working Path.

Now load the selection again, and return to Layers tab. Click Add Layer Mask once to create a Layer Mask (Command-click to load again) then click the same button( 6b) once more to Add Vector Mask. Saving selections as Vector Masks or Shapes saves memory.

Selecting with Vector Mask

Click on the Vector Mask to activate it. Or selecting any of the Shape tools will make it active. Vector Masks are modified by adjusting the spline positions (Control Points) and curvature (Tangents). You can disable, delete, or save the Layer Mask with another Layer. The Convert Point tool is most suitable for altering Vector shapes and Paths. Click and drag on the handles, then Command-click on control points to move them.

Once a acceptable outline has been achieved use the Add Points tool to refine and further match the outlines. Delete points when necessary. Dragging handles with Command + Shift will lock their relative slopes. Drag directly on the Control Point to reset handles. Regular curvy shapes are best to be extracted with this process.

This method is also best in situations where boundaries are not clearly visible.

Select by Color Range

Selecting by color is the fastest way to Chroma select. Click Select > Color Range and select a color with the Eyedropper Tool available. Once selected certain shades can be removed selectively with the Minus (-) Eyedropper or again added with the Plus (+) Eyedropper. There is also a preview window that displays the selected region or the original image.

This tool can be used to setup Garbage Masks around the subject and later refine it with editing the Mask. Select by color is not a one-click solution, but does a great job in minimizing manual work.

Chroma from Channels

Color information of each type are stored in as separate channels, which can be viewed in the Channels Tab. We can use the channel wise variations in color intensities for selecting objects in the image. This process is helpful only when background and foreground have separate color distribution in at least one channel.

Advanced Chroma

In the Histogram we can see that the blue channel is predominant in the image and it extends up to the highlights where other channels are very weak. Our subject here is the patch of vegetation in foreground.

Picking the Best Channel

A simple observation of the three channels tell us that the blue channel has the highest contrast between the Sky and Grass. We are going to exploit this property to separate the two. Duplicate (Command + J) the Layer and go to the Blue channel of the Copied layer. Click Image > Adjustments > Curves or Press Command + M to apply curves modification on the current channel.

Applying Curves

Select the point closer to the dark grays of the channel and drag it (2) forward in the x-axis (horizontally) keeping y-axis at 0 (shown by the small circle). This will make the darker pixels uniformly more darker. It shouldn’t affect the background, drag it a little back to left if it does.

Next, select another point closer to the White Point, drag it (3) back towards the midtones keeping the y-axis(vertical) at maximum (shown by the small circle). What we are doing is saturating the dragged range of blue up to 100%. Make sure the whole background turns white or almost so, and there is a very high contrast between the Grass and Sky.

Channel as Mask

Command-click on the channel thumbnail to load the channel into the selection. Areas which are predominantly blue will be selected totally and the rest according to respective degrees. Areas which have no blue (the black parts) will be left from the selection. With the selection in place go to the Layers tab and click Add Layer Mask to save the selection as a Mask.

Inverting the Mask

Press Command + I to invert the Layer Mask.

Selecting by Brushing on Masks

Brush based selection is used to extract foregrounds with complex outlines with accuracy. It is also used to refine selections made with other techniques. And it also support transparency (softness).

Erasing is probably the first thing that comes to mind when we talk about brush based selection. But it is not a recommended process at all. Erasing is a destructive process and can permanently damage the original image as recovery is limited only to a number of undo levels we have set.

Brushing with Layer Masks

Here too Layer Masks can be used, to preserve the workflow of Eraser and additional possibility of recoveringremoved portions if they are needed. Painting on the Layer Mask with a White or Black will reveal or hide the contents respectively. We can brush out backgrounds in the same way as in using the Eraser tool and get it back by painting with White.

No Feedback

When brushing the mask we may sometimes trim off relevant parts accidently and keep focusing on the wrong silhouette only to be discovered later. This is highly probable when foreground background have similar hues and there is no immediate visual feedback.

Immediate Feedback

This problem can be averted by following a simple rule of keeping a multiplied duplicate of the current layer in the background as a guide layer. Multiplied gradient maps will show-up as high contrast versions of the subject outlines if violated.

Luma Select

As already mentioned Luma is the illumination levels of an image. Luma can be used to extract components from the image which have a considerable brightness difference than others.

Simplest Luma Hack

Unlock the background and make a duplicate of it, then hide the original Layer.

Apply Threshold

Apply a Threshold Adjustment Layer on top. You will notice that some parts of the image have been turned instantly black and rest are pure white, and there are no intermediate grayscale levels.

Adjust Threshold

Adjust the Threshold Slider and try to enclose the subject or background (whichever is darker) in black. Hide the Threshold layer and look at the original image for guidance when required.

Merge Layers

Command-click to select the top two layers and Merge them into one. Select the bottom layer, make it visible and create a blank Layer Mask.

Add Layer Mask

Copy the merged image and paste to the Layer Mask, following the process discussed above. We have our Layer Mask ready, but in most cases there will be holes and parts of our background visible. Use the Mask Painting technique discussed above to make it tidy. Invert if necessary.

Luma Select with Transparency

The Threshold technique discussed above is very fast to implement, but is only useful for extracting solid objects as it lacks transparency. The following method can be useful in situations where we need Luma extraction with transparency. Here we are going to remove the ice-water from the rest of the rocks.

Using Luma to Mask with Transparency

Unlock and Create a layer from the background (1). Apply an Adjustment Layer Black and White on top and then a Brightness-Contrast Adjustment Layer above it.

Reduce Brightness

Select Use Legacy mode and slowly move the Brightness slider to left, try to get as many black areas from the rocks as possible. This process will reduce the brightness of the Water too so don’t overdo it.

Increase Contrast

Now slowly increase the Contrast slider to the right. With each increase dark-grays will turn to black and lighter grays will glow more brightly. We are going to get the whites as opaque and grays as semi-transparent. Try to get both Whites and Grays where necessary. Over increasing the contrast will make it look like a Threshold Layer, if so there will be no translucency left.

Merge the Layers

When satisfied with the results Merge the top three Layers. Go to the background layer and Add a Layer Mask and copy the merged Layer into the Layer Mask.

Yet Another Possibility

Other than the above two procedures there is also another way of Luma based extraction using the Lab color method.

Lab Color Technique

Open an image and turn it to Lab Color mode by clicking Image> Mode> Lab Color. Goto Channels Tab and find the lightness channel or press Ctrl+1 to directly select it. This is where the illumination levels of all pixels are indexed in the Lab Color mode. You can play with that channel and try to isolate some element from the background. Don’t forget to duplicate the Layer or the Channel before you alter any channel.

And filters that doesn’t work on the image in Lab Color mode works on the Lightness channel, and yield almost similar results.

Conclusion

Photoshop has quite a few options when it comes to selection techniques. Try applying some of these solutions in your workflow to increase your productivity and effectiveness.

]]> http://bhuwant.com.np/blog/2009/07/a-comprehensive-introduction-to-photoshop-selection-techniques/feed/ 0 http://bhuwant.com.np/blog/2009/07/photoshop-selection-techniques/ http://bhuwant.com.np/blog/2009/07/photoshop-selection-techniques/#comments Wed, 15 Jul 2009 12:26:50 +0000 admin http://bhuwant.com.np/?p=317 0px; padding-right: 0px; padding-left: 0px; outline-width: 0px; outline-style: initial; outline-color: initial; font-style: inherit; vertical-align: baseline; font-family: Helvetica, Arial, sans-serif; font-weight: bold; color: #27221f; font-size: 2.7em; letter-spacing: -0.04em; line-height: 1.05em; padding-bottom: 10px; margin-top: 30px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; border: 0px initial initial;”>Selection in Photoshop

Photoshop selects pixels based one of the three properties, as shown in the image below:

1. Chroma: is the color of the pixel. Color of a pixel is the level of RGB values and color based select tools like the Magic Wand. Select by color uses the RGB% as a criteria to group pixels based on the set tolerance values.
2. Luma: is a selection based on Illumination levels. Illumination levels are whiteness of the image, which is nothing but higher values for all the three R, G and B channels. Photoshop doesn’t have a native interface for a Luma based selection, but many existing tools can be hacked to get a similar result.
3. Masks: are based on spatial position. Pixels are selected and discarded or masked by a parallel layer bound to corresponding image layer. Masks are grayscale and brightness of the mask is called an Alpha level, which is the degree of opaqueness of the corresponding layer pixel. It’s also called the Transparency/Opacity channel as in RGBA etc.

A Note on Masks

In this article, words like Masks and Alpha will be used interchangeably. The process of transferring images to layer masks will be shown once and then used repeatedly without explicitly mentioning thereafter.

Step 1

Open a new image that you want to use as a mask. Double-click the background layer and create a new layer, which is “Layer 0.” Make a new layer, which is “Layer 1,” on top of it and fill with a uniform color, then hide “Layer 1.”

Step 2

Go to “Layer 0″ and click Select > Select All (Command + A) to select all pixels. Next, click Edit > Copy (Command + C) to copy all pixels to the clipboard.

Step 3

Go to “Layer 1″ and create an empty Layer Mask. Initially an all transparent Layer Mask will be created. Alt-click the layer mask to see it in the canvas.

Step 4

With the Layer Mask visible, paste onto the canvas by clicking Edit > Paste (Command + V). A grayscale version of the copied image will be pasted in as the layer mask.

Step 5

Click on the fill layer thumbnail (not mask) to see the result. Any image can be applied as a Layer Mask to another layer. The opacity of the layer will be controlled by grayscale level of the mask.

More on Masks

The easiest way of creating a Layer Mask is to click the Add Layer Mask button with something selected on the canvas. The selection will be saved as a layer mask attached to the current layer and everything outside the selection marquee will be masked and hidden.

Activate Layer Masks

Alt-clicking on the Layer Mask makes it active for editing. Only activated layer masks can be edited which are represented by a thin white outline around them.

Add Shapes to Layer Masks

Dragging any shape onto the canvas while a layer mask has been activated will draw it on the Mask instead of the layer itself. To draw it again on the layer we need to deactivate the Mask by clicking on the layer thumbnail.

Add Brush Strokes to Layer Masks

The same is true for brush strokes. Anything painted on the canvas with a Layer Mask selected will draw it on the Mask instead of the Layer. We can use this property to select objects with irregular boundaries from backgrounds, by painting everything else black on the Layer Mask. White brush strokes will reveal and blacks will conceal.

Copying a Layer Mask to Another Layer

Finally, we can transfer the Layer Mask to another layers by simply loading it as a selection (Command-click) and unloading as we did in the first step by clicking the Add Layer Mask button. Or by Alt-dragging the mask to another Layer (Not Shown).

Technique One: Images with Plain Backgrounds

The best photos are those professional studio type shots that are taken against a plain white background. These shots make it much easier to find the edges of the subject, but trimming out fine hairs can still be a little tricky. In this example we’ll be using the common Channel technique to trim out this lovely lady.

Open up your image in Photoshop. This particular image doesn’t have a pure white background, but it is a plain colour and has good contrast between the subject and grey backdrop.

Head over to the Channels palette and review each of the Red, Green and Blue channels. Each one will be made up of slightly different tones, pick the one with the most contrast between foreground and background. Drag this channel onto the new channel icon to duplicate it.

With only the new channel selected, adjust the Levels (CMD+L) to dramatically increase the contrast between light and dark areas. However, don’t go too far, as you’ll notice some horrendous pixilation appearing in the fine areas.

Due to the slight variation in tone of the background, it appears grey in the darker areas. Use the Dodge tool set to a low Opacity to target the highlights and brush over this background area to really brighten it up.

Switch over to the Burn tool and target the shadows to dramatically darken down the inner areas of the image to pure black.

Use the brush tool to finish off the blacks by painting over the remaining areas of the inner section of the image.

Inverse the image to switch over the black and white areas (CMD+I), and give a quick check for any stray areas that may have been missed by the brush.

CMD+Click the Channel thumbnail to load the selection, then turn back on the visibility of the original channels. Head back over to the Layers palette and copy the selection. Paste it on a new layer and hide the original to see the cut out image against transparency.

The selection has managed to trim out even the finest of hairs to give a realistic cut. Paste the photo against an alternate background. Zoom in and check for any light coloured fringes around the edges, especially if placed against a darker background. These can be reduced using the Burn tool set to Highlights and gently brushed over the outline of the image.

Technique Two: Images with Detailed Backgrounds

The Channels technique is all well and good for studio photography with plain backgrounds, but it gets a little more difficult on standard shots with detailed backgrounds getting in the way.

Open up your image in Photoshop. This image has a decent contrast between foreground and background, but certain areas of the hair do blend in with the darker tones of the backdrop.

Start by trimming out the clear edges with the Pen Tool, but when you reach the hair simply create a rough tracing.

Around the hair portion, aim to include only solid areas of hair that aren’t merging with the background, otherwise the lighter tones will mess things up later.

Make a selection with a feathering of 0.2 pixels to remove any harsh edges then paste onto a new layer. Reduce the transparency of the image so that the original hair line can just be seen.

Here’s where the fun begins! Use the Smudge Tool to draw in areas of new hair, using the original outline as a template. Begin with a 4px brush to flesh out the thick base hair and disguise the jaggy lines from the path. A Wacom Graphics Tablet really comes in handy here to speed up the process and help add varied line thicknesses.

The new hair will soon flesh out the image back to its original appearance. It doesn’t look too bad at this stage, but repeating the process with a thinner brush will draw in those individual hairs.

Use a 2px brush with the Smudge Tool to draw thin stray hairs in varied directions to add realism to the image.

The photo can then be placed on any background with ease, and displays a crisp cut-out with no fringing or loss of fine detail.

This is the first set of the 10 most useful shortcut keys on Mac that you really need to get a hang of to be productive in everyday use. 

• shift + apple key (command) + delete – empty trash
• ctrl + n – new mail window (in Mail application)
• shift + apple key + d – send mail
• apple key + w – close active window
• shift + apple key + left/right arrow – tab navigation in Safari browser
• mouse drag and drop + hold option – copy file
• mouse drag and drop + hold option + apple – create alias (shortcut)
• apple + space – on/off spotlight (search)
• apple + tab – switch to another active app
• apple + q – quit active application

For a brochure whose primary purpose is to advertise or market products and services, the cover will most likely have two parts: a catchy phrase that grabs the potential customer’s attention, and then lists the benefits of the product (what will this product do for me?). In the instance of a brochure that is primarily educational or informative, the product generally appears on the cover with the information of what it does or can do listed inside. The entertaining brochure is used the least. You might see it in a family-style restaurant, for example, and it contains puzzles, drawings, etc. for kids to keep them occupied. But, for this piece, I’ll focus on the first two types of brochures.
The next thing you and the client need to decide is the number of panels in the brochure, which is influenced by a number of factors. Some questions to consider:
· How much information will be in this brochure?
· How is this brochure going to be used?
· Is there a bleed?
· Is the brochure going to be of a unique design that might include die-cuts or unusual folding?
· Will the brochure be a direct mail piece? If so, what are the postal regulations for the size and mailing costs?
· Also under mailing, will there be a returned piece such as a Business Reply Card (BRC)?
· What is the allotted budget for the brochure?
Designers need to get the parameters and specifications from the client before they proceed, as these may greatly affect the cost. Printers can also be a tremendous resource in explaining how a brochure’s parameters and specifications will affect everything from the size of paper a brochure is printed on, to trimming, folding, and special cuts.
Once those decisions are made, the graphic designer and client need to discuss what is often referred to as the “hierarchy of information” or what’s the order of information; starting with the most important and moving onto the least. At this stage, you’ll need to know on which panel or panels information is being placed. In some brochures, information (particularly photographs and maps) can go across two panels to striking effect. At the same time, when thinking about how the brochure will be laid out, consider whether each individual panel will hold distinct information or are the panels related?
You’re still not quite ready to move into the actual design process as you need to refer back to that target audience the brochure is aimed at. Here you need to know the answer to the following question: what is the message the client is sending with this brochure? Advertising, educating, informing, and entertaining are how that message is presented; the actual message is what you want to say about the particular product, service, or company.
When all that information is gathered, you can finally get down to the business of designing. You’ll take into account the basic elements of good design – alignment, repetition for a sense of unity, contrast and a focal point that provides interest, balance, scale and perspective, color, and so on. You’ll also want to keep in mind the font, size, color, and orientation of the text.
As with any design there are also things you’ll want to avoid. These include:
· Avoid over-used typefaces, two of which are Arial and Helvetica.
· For content type, keep the point size under 12.
· Don’t use more than three type faces in a brochure.
· Generally don’t use more than one alignment.
As you can see, designing even a standard six-panel brochure is often a much more complicated process than you initially might think. The more organized you are, the easier the graphic design process will be, and probably a lot more fun. With any design project, it’s a good idea to have all the necessary information, pictures, parameters, and specifications before you let your creative juices flow.

In addition, you’ll find recommended books on graphic design, design and typography, typography, Web design business, graphic design business, freelancing, Web design and layout, and more.

Fonts
Within the Fonts category you’ll find annotated high quality resources to many of the best font sites available for free fonts, shareware fonts, dingbats, font foundries, and font collections, along with font-related programs and utilities, font-specific search engines, and related information.

Graphics
Graphics are visual presentations on some surface, such as a wall, canvas, computer screen, paper, or stone to brand, inform, illustrate, or entertain. Examples are photographs, drawings, Line Art, graphs, diagrams, typography, numbers, symbols, geometric designs, maps, engineering drawings, or other images. Graphics often combine text, illustration, and color. Graphic design may consist of the deliberate selection, creation, or arrangement of typography alone, as in a brochure, flier, poster, web site, or book without any other element. Clarity or effective communication may be the objective, association with other cultural elements may be sought, or merely, the creation of a distinctive style.

Graphics can be functional or artistic. The latter can be a recorded version, such as a photograph, or an interpretation by a scientist to highlight essential features, or an artist, in which case the distinction with imaginary graphics may become blurred.

Logo Design
Within the Logo Design section below you’ll find a wide range of annotated links to logo design tutorials, logo design principles and tutorials, typography and logo design, and more. You’ll also find helpful Web sites and blogs devoted to logo design and related design topics.

In addition, you’ll find recommended books on logo design, logo design and typography, typography, and related topics.

Typography
Within the Typography section you’ll find helpful annotated links to Web site typography articles, tutorials, resources, tools, discussion lists and typography organizations, and typography book reviews and recommendations. Typography articles and tutorials topics include typography in general, Web site typography, such as choosing fonts for web sites, accessibility and typography, readability, white space, and typography, CSS, typography, and CSS typography techniques, design and typography for Web sites, image replacement techniques (IFR, sIFR, swfIR, others), and font design and creation. The typography tools section include typography and fonts software, such as font creation software, font conversion software, font management software programs and utilities, viewers, utilities, software and online tools to help identify fonts, printed and online font reference charts, cross-browser, cross-platform font charts and references, and more related to typography in general, but especially Web site typography. You’ll also find short reviews of recommended books on typography, fonts, and lettering.

Access (Microsoft Access)
A database system developed by Microsoft. Part of Microsoft Office Professional. Mostly used on low traffic web sites running on the Windows platform.

ActiveMovie
A web technology for streaming movies from a web server to a web client. Developed by Microsoft.

ActiveX
A programming interface (API) that allows web browsers to download and execute Windows programs. (See also Plug-In)

Address
See Web Address.

Anchor
In web terms: The starting point or ending point of a hyperlink.
Learn more about links in our HTML tutorial

Anonymous FTP
See FTP Server.

ANSI (American National Standards Institute)
An organization that creates standards for the computer industry. Responsible for the ANSI C standard.

ANSI C
An international standard for the C programming language.

ADO (ActiveX Data Object)
A Microsoft technology that provides data access to any kind of data store.
Learn more about ADO in our ADO tutorial

ADSL (Asymmetric Digital Subscriber Line)
A special type of DSL line where the upload speed is different from the download speed.

Amaya
An open source web browser editor from W3C, used to push leading-edge ideas in browser design.

Animation
A set of pictures simulating movement when played in series.

Anti-Virus Program
A computer program made to discover and destroy all types of computer viruses.

Apache
An open source web server. Mostly for Unix, Linux and Solaris platforms.

Applet
See web applet.

Archie
A computer program to locate files on public FTP servers.

API (Application Programming Interface)
An interface for letting a program communicate with another program. In web terms: An interface for letting web browsers or web servers communicate with other programs. (See also Active-X and Plug-In)

ARPAnet
The experimental network tested in the 1970’s which started the development of the Internet.

Authentication
In web terms: the method used to verify the identity of a user, program or computer on the web.

ASCII (American Standard Code for Information Interchange)
A set of 128 alphanumeric and special control characters used for computer storing and printing of text. Used by HTML when transmitting data over the web.
See the full list of ASCII codes in our HTML Reference

ASF (Advanced Streaming Format)
A multimedia streaming format. Developed by Microsoft for Windows Media.

ASP (Active Server Pages)
A Microsoft technology allowing the insertion of server executable scripts in web pages.
Learn more about ASP in our ASP tutorial

ASX (ASF Streaming Redirector)
An XML format for storing information about ASF files. Developed by Microsoft for Windows Media.

AVI (Audio Video Interleave)
File format for video files. Video compression technology developed by Microsoft.

Banner Ad
A (most often graphic) advertisement placed on a web page, which acts as a hyperlink to an advertiser’s web site.

Bandwidth
A measure for the speed (amount of data) you can send through an Internet connection. The more bandwidth, the faster the connection.

Baud
The number of symbols per second sent over a channel.

BBS (Bulletin Board System)
A web based public system for sharing discussions, files, and announcements.

Binary Data
Data in machine readable form.

Bit (Binary Digit)
The smallest unit of data stored in a computer. A bit can have the value of 0 or 1. A computer uses 8 bits to store one text character.

BMP (Bitmap)
A format for storing images.

Bookmark
In web terms: A link to a particular web site, stored (bookmarked) by a web user for future use and easy access.

Browse
Term to describe a user’s movement across the web, moving from page to page via hyperlinks, using a web browser. (See Web Browser).

BPS (Bits Per Second)
Term to describe the transmission speed for data over the web.

Browser
See Web Browser.

Byte (Binary Term)
A computer storage unit containing 8 bits. Each byte can store one text character.

C
An advanced programming language used for programming advanced computer applications.

C++ (C Plus Plus)
The same as C with added object-oriented functions.

C# (C Sharp)
A Microsoft version of C++ with added Java-like functions.

Case Sensitive
A term used to describe if it is of importance to use upper or lower case letters.

Cache
In web terms: A web browser or web server feature which stores copies of web pages on a computer’s hard disk.

Chat
An on-line text-based communication between Internet users.

CGI (Common Gateway Interface)
A set of rules that describes how a CGI program communicates with a web server.

CGI Bin
The folder (or directory) on a web server that stores CGI programs.

CGI Program
A small program that handles input and output from a web server. Often CGI programs are used for handling forms input or database queries.

Cinepac
A codec for computer video.

Client
See Web Client.

Client/Server
In web terms: The communication and separation of workload between a web client and a web server.

Click
In web terms: A mouse click on a hyperlink element (such as text or picture) on a web page which creates an event such as taking a visitor to another web page or another part of the same page.

Clickthrough Rate
The number of times visitors click on a hyperlink (or advertisement) on a page, as a percentage of the number of times the page has been displayed.

Codec (Compressor / Decompressor)
Common term for the technology used for compressing and decompressing data.

Communication Protocol
A standard (language and a set of rules) to allow computers to interact in a standard way. Examples are IP, FTP, and HTTP.
Learn more about Communication Protocols in our TCP/IP tutorial

Compression
A method of reducing the size (compress) of web documents or graphics for faster delivery via the web.

Computer Virus
A computer program that can harm a computer by displaying messages, deleting files, or even destroying the computer’s operating system.

Cookie
Information from a web server, stored on your computer by your web browser. The purpose of a cookie is to provide information about your visit to the website for use by the server during a later visit.

ColdFusion
Web development software for most platforms (Linux, Unix, Solaris and Windows).

CSS (Cascading Style Sheets)
A W3C recommended language for defining style (such as font, size, color, spacing, etc.) for web documents.
Learn more about CSS in our CSS tutorial

Database
Data stored in a computer in such a way that a computer program can easily retrieve and manipulate the data.
Learn more about databases in our SQL tutorial

Database System
A computer program (like MS Access, Oracle, and MySQL) for manipulating data in a database.

DB2
A database system from IBM. Mostly for Unix and Solaris platforms.

DBA (Data Base Administrator)
The person (or the software) who administers a database. Typical task are: backup, maintenance and implementation.

DHCP (Dynamic Host Configuration Protocol)
An Internet standard protocol that assigns new IP addresses to users as need.

DHTML (Dynamic HTML)
A term commonly to describe HTML content that can change dynamically.
Learn more about DHTML in our DHTML tutorial

Dial-up Connection
In web terms: A connection to Internet via telephone and modem.

Discussion Group
See Newsgroup.

DNS (Domain Name Service)
A computer program running on a web server, translating domain names into IP addresses. Learn more about DNS in our Web Hosting tutorial

DNS Server
A web server running DNS.

DOM (Document Object Model)
A programming model for web page objects. (See HTML DOM and XML DOM)

Domain Name
The name that identifies a web site. (like: W3Schools.com)
Learn more about domains in our Web Hosting tutorial

DOS (Disk Operating System)
A general disk based computer operating system (see OS). Originally developed by Microsoft for IBM personal computers. Often used as a shorthand for MS-DOS.

Download
To transfer a file from a remote computer to a local computer. In web terms: to transfer a file from a web server to a web client. (see also Upload).

DSL (Digital Subscriber Line)
An Internet connection over regular telephone lines, but much faster. Speed may vary from 128 kilobit per second, up to 9 megabit per second.

DTD (Document Type Definition)
A set of rules (a language) for defining the legal building blocks of a web document like HTML or XML.
Learn more about DTD in our DTD tutorial

Dynamic IP
An IP address that changes each time you connect to the Internet. (See DHCP and Static IP).

E-mail (Electronic Mail)
Messages sent from one person to another via the Internet.

E-mail Address
The address used for sending e-mails to a person or an organization. Typical format is username@hostname.

E-mail Server
A web server dedicated to the task of serving e-mail.

Encryption
To convert data from its original form to a form that can only be read by someone that can reverse the encryption. The purpose of encryption is to prevent unauthorized reading of the data.

Error
See Web Server Error.

Ethernet
A type of local area network (see LAN).

Firewall
Software that acts as a security filter that can restrict types of network communication. Most often used between an individual computer (or a LAN) and the Internet.

Flash
A vector-based multimedia format developed by Macromedia for use on the web.
Learn more about Flash in our Flash tutorial

Form
See HTML Form.

Forum
In web terms: The same as Newsgroup.

Frame
In web terms: A part of the browser screen displaying a particular content. Frames are often used to display content from different web pages.

FrontPage
Web development software for the Windows platform. Developed by Microsoft.

FTP (File Transfer Protocol)
One of the most common methods for sending files between two computers.

FTP Server
A web server you can logon to, and download files from (or upload files to). Anonymous FTP is a method for downloading files from an FTP server without using a logon account.

Gateway
A computer program for transferring (and reformatting) data between incompatible applications or networks.

GIF (Graphics Interchange Format)
A compressed format for storing images developed by CompuServe. One of the most common image formats on the Internet.

GB
Same as Gigabyte. 10GB is ten gigabytes.

Gigabyte
1024 megabytes. Commonly rounded down to one billion bytes.

Graphics
In web terms graphics describe pictures (opposite to text).

Graphic Monitor
A display monitor that can display graphics.

Graphic Printer
A printer that can print graphics.

Graphical Banner
See Banner Ad.

Helper application
In web terms: A program helping the browser to display, view, or work with files that the browser cannot handle itself. (See Plug-In).

Hits
The number of times a web object (page or picture) has been viewed or downloaded. (See also Page Hits).

Home Page
The top-level (main) page of a web site. The default page displayed when you visit a web site.

Host
See Web Host.

Hosting
See Web Hosting.

Hotlink
See Hyperlink.

HTML (Hypertext Markup Language)
HTML is the language of the web. HTML is a set of tags that are used to define the content, layout and the formatting of the web document. Web browsers use the HTML tags to define how to display the text.
Learn more about HTML in our HTML tutorial

HTML Document
A document written in HTML.

HTML DOM (HTML Document Object Model)
A programming interface for HTML documents.
Learn more about HTML DOM in our HTML DOM tutorial

HTML Editor
A software program for editing HTML pages. With an HTML editor you can add elements like lists, tables, layout, font size, and colors to a HTML document like using a word processor. An HTML editor will display the page being edited exactly the same way it will be displayed on the web (See WYSIWYG).

HTML Form
A form that passes user input back to the server.
Learn more about HTML forms in our HTML tutorial

HTML Page
The same as an HTML Document.

HTML Tags
Code to identify the different parts of a document so that a web browser will know how to display it.
Learn more about HTML tags our HTML tutorial

HTTP (Hyper Text Transfer Protocol)
The standard set of rules for sending text files across the Internet. It requires an HTTP client program at one end, and an HTTP server program at the other end.

HTTP Client
A computer program that requests a service from a web server.

HTTP Server
A computer program providing services from a web server.

HTTPS (Hyper Text Transfer Protocol Secure)
Same as HTTP but provides secure Internet communication using SSL. (see also SSL)

Hyperlink
A pointer to another document. Most often a pointer to another web page. A hyperlink is a synonym for a hotlink or a link, and sometimes called a hypertext connection to another document or web page.

Hypermedia
An extension to hypertext to include graphics and audio.

Hypertext
Hypertext is text that is cross-linked to other documents in such a way that the reader can read related documents by clicking on a highlighted word or symbol. (see also hyperlink)

IAB (Internet Architecture Board)
A council that makes decisions about Internet standards. (See also W3C).

IE (Internet Explorer)
See Internet Explorer.

IETF (Internet Engineering Task Force)
A subgroup of IAB that focuses on solving technical problems on the Internet.

IIS (Internet Information Server)
A web server for Windows operating systems. Developed by Microsoft.

IMAP (Internet Message Access Protocol)
A standard communication protocol for retrieving e-mails from an e-mail server. IMAP is much like POP but more advanced.
Learn more about IMAP in our TCP/IP tutorial

Indeo
A codec for computer video developed by Intel.

Internet
A world wide network connecting millions of computers. (See also WWW)

Internet Browser
See Web Browser.

Internet Explorer
A browser by Microsoft. The most commonly used browser today.
Learn more about browsers in our browser section

Internet Server
See Web Server

Intranet
A private (closed) Internet, running inside a LAN (Local Area Network).

IP (Internet Protocol)
See TCP/IP.

IP Address (Internet Protocol Address)
A unique number identifying every computer on the Internet (like 197.123.22.240)

IP Number (Internet Protocol Number)
Same as an IP address.

IP Packet
See TCP/IP Packet.

IRC (Internet Relay Chat)
An Internet system that enables users to take part in on-line discussions.

IRC Client
A computer program that enables a user to connect to IRC.

IRC Server
An Internet server dedicated to the task of serving IRC connections.

ISAPI (Internet Server API)
Application Programming Interface (See API) for Internet Information Server (See IIS).

ISDN (Integrated Services Digital Network)
A telecommunication standard that uses digital transmission to support data communications over regular telephone lines.

ISP (Internet Service Provider)
Someone that provides access to the Internet and web hosting.

Java
A programming language developed by SUN. Mostly for programming web servers and web applets.

Java Applet
See Web Applet.

JavaScript
The most popular scripting language on the internet, developed by Netscape.
Learn more about JavaScript in our JavaScript tutorial.

JPEG (Joint Photographic Expert Group)
The organization that promotes the JPG and JPEG graphic formats for storing compressed images.

JPEG and JPG
Graphic formats for storing compressed images.

JScript
Microsoft’s version of JavaScript.

JSP (Java Server Pages)
A Java based technology allowing the insertion of server executable scripts in web pages. Mostly used on Linux, Unix and Solaris platforms.

K
Same as kilobyte 10K is ten kilobytes..

KB
Same as kilobyte 10KB is ten kilobytes..

Keyword
In web terms: A word used by a search engine to search for relevant web information.
In database terms: A word (or index) used to identify a database record.

Kilobyte
1024 bytes. Often called 1K, and rounded down to 1000 bytes.

LAN (Local Area Network)
A network between computers in a local area (like inside a building), usually connected via local cables. See also WAN.

Link
The same as a hyperlink.

Linux
Open source computer operating system based on Unix. Mostly used on servers and web servers.

Mail
In web terms: the same as e-mail.

Mail Server
See e-mail server.

MB
Same as Megabyte. 10MB is ten megabytes.

Megabyte
1024 kilobytes. Commonly rounded down to one million bytes.

Meta Data
Data that describes other data. (See also Meta Tags).

Meta Search
The method of searching for meta data in documents.

Meta Tags
Tags inserted into documents to describe the document.
Learn more about meta tags in our HTML tutorial

MIDI (Musical Instrument Digital Interface)
A standard protocol for communication between computers and musical instruments.
Learn more about MIDI in our Media tutorial

MIME (Multipurpose Internet Mail Extensions)
An Internet standard for defining document types. MIME type examples: text/plain, text/html, image/gif, image/jpg.
Learn more about MIME types in our Media tutorial

MIME Types
Document types defined by MIME.

Modem
Hardware equipment to connect a computer to a telephone network Typically used to connect to the Internet via a telephone line.

Mosaic
The first commonly available web browser. Mosaic was released in 1993 and started the popularity of the web.

MOV
A codec for computer video developed by Apple. Common file extension for QuickTime multimedia files.

MP3 (MPEG-1 Audio Layer-3)
An audio compression format specially designed for easy download over the Internet.

MP3 File
An file containing audio compressed with MP3. Most often a music track.

MPEG (Moving Picture Expert Group)
An ISO standard codec for computer audio and video.

MPG
Common file extension for MPEG files.

MS-DOS (Microsoft Disk Operating System)
A general disk based computer operating system (See OS). Originally developed by Microsoft for IBM computers, then developed by Microsoft as a basis for the first versions of Windows.

Multimedia
In web terms: A presentation combining text with pictures, video, or sound.

MySQL
Free open source database software often used on the web.

NetBEUI (Net Bios Extended User Interface)
An enhanced version of NetBIOS.

NetBIOS (Network Basic Input Output System)
An application programming interface (API) with functions for local-area networks (LAN). Used by DOS and Windows.

Navigate
In web terms: The same as Browse.

Netscape
The browser from the company Netscape. The most popular browser for many years. Today IE has the lead.
Learn more about browsers in our browser section

Newsgroup
An on-line discussion group (a section on a news server) dedicated to a particular subject of interest.

News Reader
A computer program that enables you to read (and post messages) from an Internet newsgroup.

News Server
An Internet server dedicated to the task of serving Internet newsgroups.

Node
In web terms: A computer connected to the Internet, most often used to describe a web server.

Opera
The browser from the company Opera.
Learn more about browsers in our browser section

OS (Operating System)
The software that manages the basic operating of a computer.

Packet
See TCP/IP Packet.

Page Hits
The number of times a web page has been visited by a user.

Page Impressions
The same as Page Hits.

Page Views
The same as Page Hits.

PDF (Portable Document Format)
A document file format developed by Adobe. Most often used for text documents.

Perl (Practical Extraction and Reporting Language)
A scripting language for web servers. Most often used on Unix servers.

PHP (PHP: Hypertext Preprocessor)
A technology allowing the insertion of server executable scripts in web pages. Mostly for Unix, Linux and Solaris platforms.
Learn more about PHP in our PHP tutorial.

Ping
A method used to check the communication between two computers. A “ping” is sent to a remote computer to see if it responds.

Platform
In web terms: The computer’s operating system like Windows, Linux, or OS X.

Plug-In
An application built into another application. In web terms: A program built in (or added) to a web browser to handle a special type of data like e-mail, sound, or movie files. (See also ActiveX)

PNG (Portable Network Graphics)
A format for encoding a picture pixel by pixel and sending it over the web. A W3C recommendation for replacing GIF.

POP (Post Office Protocol)
A standard communication protocol for retrieving e-mails from an e-mail server. (See also IMAP).
Learn more about POP and IMAP in our TCP/IP tutorial

Port
A number that identifies a computer IO (input/output) channel. In web terms: A number that identifies the I/O channel used by an Internet application (A web server normally uses port 80).

Protocol
See Communication Protocol.

PPP (Point to Point Protocol)
A communication protocol used for direct connection between two computers.

Proxy Server
An Internet server dedicated to improve Internet performance.

QuickTime
A multimedia file format created by Apple.
Learn more about QuickTime in our Media tutorial

RAID (Redundant Array of Independent Disks)
A standard for connecting multiple disks to the same server for higher security, speed and performance. Often used on web servers.

RDF (Resource Description Framework)
A framework for constructing languages for describing web resources.
Learn more about RDF in our RDF tutorial

Real Audio
A common multimedia audio format created by Real Networks.
Learn more about Real Audio in our Media tutorial

Real Video
A common multimedia video format created by Real Networks.
Learn more about Real Video in our Media tutorial

Redirect
In web terms: The action when a web page automatically forwards (redirects) the user to another web page.

RGB (Red Green Blue)
The combination of the three primary colors that can represent a full color spectrum.
Learn more about RGB in our HTML tutorial

Robot
See Web Robot.

Router
A hardware (or software) system that directs (routes) data transfer to different computers in a network.

Schema
See XML Schema.

Script
A collection of statements written in a Scripting Language.

Scripting Language
In web terms: A simple programming language that can be executed by a web browser or a web server. See JavaScript and VBScript.

Scripting
Writing a script.

Search Engine
Computer program used to search and catalog (index) the millions of pages of available information on the web. Common search engines are Google and AltaVista.

Semantic Web
A web of data with a meaning in the sense that computer programs can know enough about the data to process it.

Server
See Web Server.

Server Errors
See Web Server Errors.

Shareware
Software that you can try free of charge, and pay a fee to continue to use legally.

Shockwave
A format (technology) developed by Macromedia for embedding multimedia content in web pages.

SGML (Standard Generalized Markup Language)
An international standard for markup languages. The basis for HTML and XML.

SMIL (Synchronized Multimedia Integration Language)
A W3C recommended language for creating multimedia presentations.
Learn more about SMIL in our SMIL tutorial

SMTP (Simple Mail Transfer Protocol)
A standard communication protocol for sending e-mail messages between computers.
Learn more about SMTP in our TCP/IP tutorial

SOAP (Simple Object Access Protocol)
A standard protocol for letting applications communicate with each other using XML.
Learn more about SOAP in our SOAP tutorial

Solaris
Computer operating system from SUN.

SPAM
In web terms: The action of sending multiple unwelcome messages to a newsgroup or mailing list.

Spider
See Web Spider.

Spoofing
Addressing a web page or an e-mail with a false referrer. Like sending an e-mail from a false address.

Spyware
Computer software hidden in a computer with the purpose of collecting information about the use of the computer.

SQL (Structured Query Language)
An ANSI standard computer language for accessing and manipulating databases.
Learn more about SQL in our SQL tutorial.

SQL Server
A database system from Microsoft. Mostly used on high traffic web sites running on the Windows platform.

SSI (Server Side Include)
A type of HTML comment inserted into a web page to instruct the web server to generate dynamic content. The most common use is to include standard header or footer for the page.

SSL (Secure Socket Layer)
Software to secure and protect web site communication using encrypted transmission of data.

Static IP (address)
An IP address that is the same each time connect to the Internet. (See also Dynamic IP).

Streaming
A method of sending audio and video files over the Internet in such a way that the user can view the file while it is being transferred.

Streaming Format
The format used for files being streamed over the Internet. (See Windows Media, Real Video and QuickTime).

SVG (Scalable Vector Graphics)
A W3C recommended language for defining graphics in XML.
Learn more about SVG in our SVG tutorial

Tag
In web terms: Notifications or commands written into a web document. (See HTML Tags)

TCP (Transmission Control Protocol)
See TCP/IP.

TCP/IP (Transmission Control Protocol / Internet Protocol)
A collection of Internet communication protocols between two computers. The TCP protocol is responsible for an error free connection between two computers, while the IP protocol is responsible for the data packets sent over the network.
Learn more about TCP/IP in our TCP/IP tutorial

TCP/IP Address
See IP Address.

TCP/IP Packet
A “packet” of data sent over a TCP/IP network. (data sent over the Internet is broken down into small “packets” from 40 to 32000 bytes long).

Trojan Horse
Computer program hidden in another computer program with the purpose of destroying software or collecting information about the use of the computer.

UDDI (Universal Description Discovery and Integration)
A platform-independent framework for describing services, discovering businesses, and integrating business services using the Internet.
Learn more about UDDI in our WSDL tutorial

Unix
Computer operating system, developed by Bell Laboratories. Mostly used for servers and web servers.

UNZIP
To uncompress a ZIPPED file. See ZIP.

Upload
To transfer a file from a local computer to a remote computer. In web terms: to transfer a file from a web client to a web server. (see also Download).

URI (Uniform Resource Identifier)
Term used to identify resources on the internet. URL is one type of an URI.

URL (Uniform Resource Locator)
A web address. The standard way to address web documents (pages) on the Internet (like: http://www.w3schools.com/)

USENET
A world wide news system accessible over the Internet. (See Newsgroups)

User Agent
The same as a Web Browser.

VB (Visual Basic)
See Visual Basic.

VBScript
A scripting language from Microsoft. VBScript is the default scripting language in ASP. Can also be used to program Internet Explorer.
Learn more about VBScript in our VBScript tutorial.

Virus
Same as Computer Virus.

Visit
In web terms: A visit to a web site. Commonly used to describe the activity for one visitor of a web site.

Visitor
In web terms: A visitor of a web site. Commonly used to describe a person visiting (viewing) a web site.

Visual Basic
A programming language from Microsoft.

VPN (Virtual Private Network)
A private network between two remote sites, over a secure encrypted virtual Internet connection (a tunnel).

VRML (Virtual Reality Modeling Language)
A programming language to allow 3D effects to be added to HTML documents.

W3C (World Wide Web Consortium)
The organization responsible for managing standards for the WWW.
Learn more about W3C in our W3C tutorial

WAN (Wide Area Network)
Computers connected together in a wide network, larger than a LAN, usually connected via phone lines. See also LAN.

WAP (Wireless Application Protocol)
A leading standard for information services on wireless terminals like digital mobile phones.
Learn more about WAP in our WAP tutorial

Web Address
The same as an URL or URI. See URL.

Web Applet
A program that can be downloaded over the web and run on the user’s computer. Most often written in Java.

Web Client
A software program used to access web pages. Sometimes the same as a Web Browser, but often used as a broader term.

Web Browser
A software program used to display web pages.
Learn more about browsers in our Browser section

Web Document
A document formatted for distribution over the web. Most often a web document is formatted in a markup language like HTML or XML.

Web Error
See Web Server Error.

Web Form
See HTML Form.

Web Host
A web server that “hosts” web services like providing web site space to companies or individuals.

Web Hosting
The action of providing web host services.

Web Page
A document (normally an HTML file) designed to be distributed over the Web.

Web Robot
See Web Spider.

Web Server
A server is a computer that delivers services or information to other computers. In web terms: A server that delivers web content to web browsers.

Web Server Error
A message from a web server indicating an error. The most common web server error is “404 File Not Found”.
Learn more about web server error messages in our HTML tutorial

Web Services
Software components and applications running on web servers. The server provides these services to other computers, browsers or individuals, using standard communication protocols.

Web Site
A collection of related web pages belonging to a company or an individual.

Web Spider
A computer program that searches the Internet for web pages. Common web spiders are the one used by search engines like Google and AltaVista to index the web. Web spiders are also called web robots or wanderers.

Web Wanderer
See Web Spider.

Wildcard
A character used to substitute any character(s). Most often used as an asterix (*) in search tools.

Windows 2000, Windows NT, Windows 95/98, Windows XP
Computer operating systems from Microsoft.

Windows Media
Audio and video formats for the Internet, developed by Microsoft. (See ASF, ASX, WMA and WMF).
Learn more about Windows Media in our Media tutorial

WINZIP
A computer program for compressing and decompressing files. See ZIP.

WMA
Audio file format for the Internet, developed by Microsoft. (See also WMV).
Learn more about media formats in our Media tutorial.

WMV
Video file format for the Internet, developed by Microsoft. (See also WMA).
Learn more about media formats in our Media tutorial

WML (Wireless Markup Language)
A standard for information services on wireless terminals like digital mobile phones, inherited from HTML, but based on XML, and much stricter than HTML.
Learn more about WML in our WAP tutorial

WML Script
Scripting language (programming language) for WML.
Learn more about WMLScript in our WMLScript tutorial

Worm
A computer virus that can make copies of itself and spread to other computers over the Internet.

WSDL (Web Services Description Language)
An XML-based language for describing Web services and how to access them.
Learn more about WSDL in our WSDL tutorial

WWW (World Wide Web)
A global network of computers using the internet to exchange web documents. (See also Internet)

WWW Server
The same as a Web Server.

WYSIWYG (What You See Is What You Get)
In Web terms: To display a web page being edited exactly the same way it will be displayed on the web.

XForms
A future version of HTML Forms, based on XML and XHTML. Differs from HTML forms by separating data definition and data display. Providing richer and more device independent user input.
Learn more about XForms in our XForms tutorial

XHTML (Extensible Hypertext Markup Language)
HTML reformulated as XML. XHTML is the latest version of HTML. Developed by W3C.
Learn more about XHTML in our XHTML tutorial

XPath
XPath is a set of syntax rules (language) for defining parts of an XML document. XPath is a major part of the W3C XSL standard.
Learn more about XPath in our XPath tutorial

XQuery
XQuery is a set of syntax rules (language) for extracting information from XML documents. XQuery builds on XPath. XQuery is developed by W3C.
Learn more about XQuery in our XQuery tutorial

XML (Extensible Markup Language)
A simplified version of SGML especially designed for web documents, developed by the W3C.
Learn more about XML in our XML tutorial

XML Document
A document written in XML.

XML DOM (XML Document Object Model)
A programming interface for XML documents developed by W3C.
Learn more about XML DOM in our XML DOM tutorial

XML Schema
A document that describes, in a formal way, the syntax elements and parameters of a web language. Designed by W3C to replace DTD.
Learn more about Schema in our XML Schema tutorial

XSD (XML Schema Definition)
The same as XML Schema.

XSL (Extensible Stylesheet Language)
A suite of XML languages developed by W3C, including XSLT, XSL-FO and XPath.
Learn more about XSL in our XSL tutorial

XSL-FO (XSL Formatting Objects)
An XML language for formatting XML documents. A part of XSL developed by W3C.
Learn more about XSL-FO in our XSL-FO tutorial

XSLT (XSL Transformations)
An XML language for transforming XML documents. A part of XSL developed by W3C.
Learn more about XSLT in our XSLT tutorial

ZIP
A compressing format for computer files. Commonly used for compressing files before downloading over the Internet. ZIP files can be compressed (ZIPPED) and decompressed (UNZIPPED) using a computer program like WINZIP.