Glossary of Internet Terms

Letter C

©2002 by Walt Howe
(last updated 22 October 2012)

Select the first character of the term you want to look up or use the Search link at the right.

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This Internet Glossary is growing. Terms and definitions are being added all the time. If you have comments, corrections, or suggested additions, please send them to Walt Howe using the form at the end of the Glossary. My thanks for the many suggestions that already have been included.

Web Developers! See how to link to terms in the glossary from your web page.


Browsers such as Netscape and Microsoft Internet Explorer hold copies of recently visited web files, both HTML and binary files, in disk memory. This disk memory space is called the cache. It offers the advantage of much quicker loading when files are stored on disk than when they must be transferred from the web. The disadvantage is that it will sometimes show you an old version of a file from your disk when a newer one is available on the web. Some large Internet service providers also cache frequently visited sites and feed them to you from their own cache when you try to visit them.

You can set the size of the cache to meet the needs of your own system and the speed of your connection. You can also set how often your system will check back to see if there is a newer version. There is a definite trade-off between faster load times and the risk of seeing outdated material.

Usually, you can check for a newer version by using the Refresh or Reload selections in your browser. If something looks out of date, always try the Refresh or Reload before trying other things.

Sometimes files in cache can become corrupted and cause problems for your browser. When you have problems diagnosing freeze-ups where they didn't occur before, one of the easy solutions to try is to delete your cache and see if it solves the problems.

Cascading Style Sheets (CSS)
Cascading Style Sheets is a technique built into version 4.0 and later browsers that support styles for pages. For example, you can set up styles for fonts and page layouts that will apply automatically to pages developed under a particular style you develop. This technique is useful, but the present version browsers from Microsoft (in particular) and other browser designers are quite different in their implementation, and what works with one is not likely to work for the other. For compatibility, care has to be taken to use common elements.
case sensitive
When matching a string of letters, it is case sensitive if capital and lower case letters must match exactly. If an operating system or a piece of software is case sensitive, it will see all of the following text strings as different:

Since upper and lower case are differently coded in computers, it takes programming to make them match at all. On the other hand, MSDOS, older versions of windows, and most search engines are programmed to recognize the above strings as identical. On the web and the Internet, basic addresses are never case sensitive, but paths and filenames may be, depending on the operating system. By basic addresses, I mean the part of the address that ends with the domain:

The above addresses will always match. The next two pairs will not necessarily match, depending on the server:

Acronym for Consumer Digital Subscriber Line. Rockwell's technology for digital modems that will use regular telephone lines and run at speeds up to 1 MBps. See ADSL and DSL.
Issues frequently arise online about censorship. When does a service provider or a mail discussion list host or a message base host have a right to delete material others have posted?

When posts are clearly illegal, such as posting a copyrighted work of text or media without permission from the copyright holder, they must be deleted as soon as they are recognized. The host or provider may become liable if they don't take action.

But what about the online blog or forum host who deletes a political post that he or she disagrees with? Is this censorship? Are there First Amendment rights to protect such posts?

Deleting a disagreeable, but legal post is certainly a form of censorship. But it has nothing to do with First Amendment rights. The First Amendment applies to governments and their agents, not to individuals. The host who deletes material does so at his or her own risk. The risk is not a legal one, but whether such a deletion meets the needs of the community that the host represents. The online host may gain or lose membership from the community, if the community at large agrees or disagrees with the action. Censorship in such cases is more a moral and social issue than a legal one.

the European Organization for Nuclear Research where the web was born. See Internet History. The original name in French was Conseil Européen pour la Recherche Nucléaire (CERN).
Common Gateway Interface. A method used by WWW pages to communicate with programs run on the web server.
chain letter
A form of spam which asks you to distribute the letter to many other people. They are against the policies of most Internet service providers, and almost always are hoaxes. Many of them promise quick ways to make money, usually on the basis of pyramid or Ponzi schemes, which are illegal. Some make pie-in-the-sky promises, for example, that Bill Gates will give everyone $1000 for just helping test his new mail distribution scheme. Many of them prey on your sympathy and tell stories of a sick child who has asked that word be spread about the illness by chain letters. They may involve the Make-a-Wish Foundation, which states that they support no chain letters. Many report a virus warning, and ask you tell everyone about it. The virus warnings are invariably hoaxes. None of these purposes are legitimate. If you have any doubt at all about the legitimacy of a chain letter, please check the Department of Energy's Computer Incident Advisory Committee (CIAC) Chain Letter Page or ask us in the Navigating the Net Forum, and we'll research it and find the answers.
Short for character set. Different character sets are used for different purposes such as the different characters used by different languages.
A form of real-time electronic communications where participants type what they want to say, and it is repeated on the screens of all other participants in the same chat. Internet Relay Chat or IRC is an Internet protocol for chat, and there are many other chat systems in services like Delphi. Other commonly used chat systems are iChat and ICQ.
Rate of change, usually high; instability caused by frequent unplanned and hard to control changes. The word evolved from its use to mean agitation in such devices as butter churns and ice cream churns. In researching the term, I found modern examples of uses of the term to refer to changes in a customer base for wireless telephone, changes in routing patterns between ISPs, changes in membership of an e-mail discussion list, changes in click-through rates in web ads, rates of change in web pages, and prolonged hard disk activity.
Classless Inter-Domain Routing. This is a change in specifying ranges of IP addresses from the old Class A, B, and C address blocks. IP addresses consist of 32 bits, usually expressed in four 8-bit numbers, such as In the old system, Class C specified 24 bits (the first three numbers in the conventional IP address), leaving all the addresses in the remaining 8 bits to be assigned by the registrant (256 addresses, less a few broadcast only addresses). Class B specified 16 bits and class A, 8 bits, leaving the balance to the registrant. Now, the IP address is followed by an IP Prefix, such as The /26 IP Prefix means that the first 26 bits of the given IP address are fixed, and the registrant has the remaining 6 bits (64 addresses) to use and assign. IP Prefixes are currently used ranging from /27 (25 or 32 addresses) to /13 (219 or 524,288 addresses.
Competitive Local Exchange Carrier. See LEC.
An individual computer on a network that runs its own programs and processes information received from a central server.
client-server architecture
In client-server architecture, the computing load is distributed among the many clients (individual computers) in a network, drawing information from central servers of the information. On the Internet, a web browser is a client that runs software locally that processes information received from central servers of the information. The opposite of client server architecture is the situation where a central powerful computer does all the processing, feeding the results to dumb terminals which do little more than communicate requests and feed back the results processed centrally.
coax, coaxial cable
A type of cable which contains two conductors, one inside and the other outside around it, separated by an insulating layer. They share the same axis, giving the cable its name co-axial. It is the same kind of cable that brings cable TV into your house.
Compression is a technique to make a file or a data stream smaller for faster transmission or to take up less storage space. There a number of programs that will compress files, such as PKZIP, WinZip, Stuffit, gnu zip, and many more. Files with the following extensions are almost always compressed files: arc, arj, gz, lha, lhz, taZ, taz, tgz, Z, zip, and zoo. See archive, second definition.
Generally, the information provided on a web page, as opposed to its design and layout. content can take the form of text, graphics, audio, video, or a searchable database.
A cookie is a short file put on your system by a web page which includes information about your usage and facilitates the current interaction. For example, it may include the information that you have logged into a passworded area already in the current session and don't need a second password check. There are many uses for cookies, they may be erased at the end of a session or retained until the next session, and they may be encrypted or in plain text. For a more thorough explanation of cookies, see the cookie section of our article on Privacy and the Cookie FAQ at
Child Online Protection Act, a 1998 act of Congress intended to protect minors from exposure to pornography. An injunction against enforcement of the Act was upheld by the Third Circuit Court of Appeals in 1999. The Supreme Court held hearings on the act in June 2001 and their ruling is awaited.
Childrens Online Privacy Protection Act, an act of Congress requiring online services to obtain parental consent before collecting any personal information on children under 13. See the FTC Summary.
copy-and-paste, cut-and-paste
The technique of copying text from one location or file to another. If the text in the original location is deleted, it is called cut-and-paste. Whether cutting or copying, the process begins by positioning the cursor at one end of the text to be copied, and clicking and dragging to the other end to highlight the text. Or if you want to copy the entire text on a page, use Edit/Select All or press Control and the letter A simultaneously.

At this point, there are three common ways to cut or copy and then paste. Which ones work may vary by the software you are using.

  1. Select Edit and then Copy or Cut from the pull-down menus in your software. Then position your cursor in the location you want to copy to, even if it is in a different window, and then select Edit and Paste.
  2. Right click on the highlighted text and select Cut or Copy. Position the cursor in the location to be copied to, and right click and select Paste.
  3. Press the Control key and the X key together to cut or Control and C to copy. Position the cursor and press Control and V to paste. With a Macintosh, substitute the Command key for the Control key.
The legal protection against copying and the specific rights allowing copying given to original works, which may be in printed or photographically or electronically stored words, music, visual arts, and performing arts. The purpose of copyright is not just to protect the rights, but to establish the rules under which copies or portions may be made to make a work more widely available. Copyright extends to electronic representations of these forms, too, although the laws governing new electronic copies in such forms as search engine indexes and browser caches needs better definition. Copyright exists on all original works from the moment they are published, whether formally registered or not and whether or not copyright markings appear on the works. Copyrights probably apply to public postings in e-mail, message bases, and newsgroups, but the law is not well tested in these areas. Copyrights are observed by most countries in the world.

For further information on copyrights, see our Copyright Guidance page, and visit the Delphi Personal Law Forum for current discussions.

country code
Most countries in the world that are connected to the Internet have been assigned two-letter country codes by the international standard ISO 3166. These two letter codes are the major domain addresses for the country. For a complete list of them, see our Country Code List.
A person who attempts to break into a network or computer system, often with the intent to steal material or perform malicious destruction of files--or just to show it can be done. See hacker, second definition. Crackers try to exploit weaknesses in system security or in some cases, the weaknesses of its users who can be tricked into revealing passwords. See social engineering.
cram, cramming
Cramming is the practice by some phone companies, yours or others, to add false charges to your phone bills for calls you never made.
See spider.
Acronym for Cyclic Redundancy Check, a technique of providing a data string added to packets of information that can be used to detect errors in the data packets. In the OSI or TCP/IP network models, CRC is added to a packet frame at the Data Link Layer.
See Cascading Style Sheets.
Chat shorthand for "see you later".
A term coined by author William Gibson in his novel Neuromancer. It represents the totality of all connected computer networks and their contents in a future world. It has become a slang term for the Internet and the information in it.
The act of registering a company name as a domain name by someone outside the company in hopes of selling it to the company for a profit. Anti-cybersquatting legislation has been introduced to make it illegal.

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For Web Developers: How to Link to the glossary terms.
You can link to any term in this glossary with a link in this form:*.html#term

Replace the asterisk in *.html with the first letter of the term you are linking to. Terms with more than one word will generally use an underline to link the words.