Cache
An area of memory that temporarily holds data for fast retrieval. Web browsers and servers both use cache to store the files from the web pages you visit. When you go back to a page, the files do not have to be downloaded all over again.
Cascading Style Sheets allow web designers to create style sheets that define how different elements, such as headers and links, appear. These style sheets can then be applied to any web page. The term cascading derives from the fact that multiple style sheets can be applied to the same web page. CSS was developed by the W3C. See Style Sheet.
Common Gateway Interface. A set of rules that allows browsers and servers to exchange information based on requests from the browser. Perl is one of the languages used for CGI scripts. See ASP, Perl, Interactivity.
A system that allows Internet users to exchange messages with other visitors to a site in real time. See Avatar.
Clickthrough
In Web advertising, an instance of a user pressing down (clicking) on a mouse button in an ad space.
The person who hires you to create a website. See Web Designer, User.
Part of a client-server system. A client is most often an application that runs on a computer that relies on a server to perform some operation. To send or receive email, for example, you use email client software.
A networking system in which processes are split between server computers, which hold files, and client computers, which can request those files and other services from the servers. See Client (2), Server.
Occurring on the client side of a client-server system. For example, JavaScripts are typically client-side because they are executed by your browser (the client). In contrast, CGI scripts are server-side because they run on the web server. See Client (2), Server-side.
An image map for which the map information and the map processing program reside on the client computer (the user's). Some older browsers do not support client-side image maps. See Server-side Image Map, Image Map.
CMYK is a scheme for combining primary pigments used for print. The C stands for cyan (aqua), M stands for magenta (pink), Y is yellow, and K stands for black. See RGB.
The acronym for "compression/decompression." A codec is an algorithm or specialized computer program that reduces the number of bytes consumed by large files and programs. See Compression.
Housing a web server off-site at a company that provides bandwidth, security, and a full-time support team. See Hosting, ISP, Remote Hosting, Server.
Compatibility
A term referring to the ability to work with cross devices or systems without modification. In web design, this often refers to cross-browser and cross-platform compatibility. The importance of a website being viewable and functional on a variety of browsers and, at a minimum, on both Windows and Mac operating systems. Because of inconsistent browser functionality and standards support, creating a cross-browser compatible site is often a frustrating and time-consuming process.
The reduction in size of data in order to save space or transmission time. See Lossy Compression, Lossless Compression, Codec.
ColdFusion
Uses its own markup language to integrate databases and web pages.
Cookies
Cookies are small data files written to your hard drive by some websites. These small pieces of information are sent from the web server and can be retrieved each time your browser requests a page from that server.
CRT
A cathode ray tube (CRT) is a specialized vacuum tube in which images are produced when an electron beam strikes a phosphorescent surface. Most desktop computer displays make use of CRTs. The CRT in a computer display is similar to the "picture tube" in a television receiver.