Letter: C
C shell
A user interface for those whose Internet providers offer only character-based, command-line access to a Unix system (hence the term "shell account").
Cache
Caching (pronounced CASH-ing) is a technique computers use to save memory by storing frequently accessed files. Similarly, Web browsers have caches that keep recently downloaded Web pages handy, often as a list of links on the browser's toolbar. Browser caches are typically kept on your local drive, and you can usually adjust the amount of memory or disk space allotted for the cache. The benefit of Web caches is that you can access a cached page much more quickly than if you downloaded it from a distant server.
Call to Action
Have you ever seen an advertisement that implored you to "Call now!"? Of course you have. Call to action is a term for the copy in an ad that implores the viewer to do something specific in response to the advertisement. "Click here" and its variants are the most popular calls to action in online advertising.
CCITT V series
Several international modem standards set by the Consultative Committee for International Telephony and Telegraphy. The standards help buyers make sure modems they buy will communicate with other modems. The standards, formerly used primarily outside the United States, have been accepted almost universally since the advent of the 2400 bits per second (bps) modems. Not all are relevant to computer users. Examples include: V.21, V.22, V.22bis, V.23, V.26, V.26bis, V.27, V.27bis, V.27ter, V.29, V.32, V.32bis, V.34, V.42, V.42bis.
CDF
Microsoft developed the channel definition format (CDF) as an application of the eXtensible markup language (XML), proposing it as a standard for push media. CDF allows Web publishers to push content at users through a channel, similar to Marimba's Castanet or Netscape's NetCaster. New content posted to a channel's Web server will push any software that supports the CDF format. One piece of software that doesn't support CDF, however, is anything written by Netscape, which uses its own NetCaster. While Microsoft has an advantage in working with the World Wide Web Consortium (W3C), it hasn't yet defined a user interface for the channels. Conversely, Marimba and Netscape aren't overtly trying to write a standard specification.
CERT
Computer Emergency Response Team) A clearinghouse of information about network security.
Certificate Authority
An issuer of Security Certificates used in SSL connections.
CFML
(Cold Fusion Markup Language) An extension of HTML. A proprietary markup language used by Allaire's Cold Fusion to link HTML pages to database servers. CFML goes beyond database management to fill some important gaps in HTML, including session variables, branching logic, loops, and other constructs that programmers are accustomed to using, such as error trapping and debugging tools.
CGI
(Common Gateway Interface) A Web server scripting standard; a mechanism used to connect script to Web servers. In the past, most CGI programs were actually script files and were often written in scripting languages like PERL. Today, scripts can also be executable programs. You can write scripts in C and Visual Basic. The CGI specification has gone through several revisions. The best place to fine up-to-date information is the World Wide Web Consortium (W3) Web site (http://www.w3.org).
CGI
(Common Gateway Interface) -- A set of rules that describe how a Web Server communicates with another piece of software on the same machine, and how the other piece of software (the “CGI program”) talks to the web server. Any piece of software can be a CGI program if it handles input and output according to the CGI standard.
Usually a CGI program is a small program that takes data from a web server and does something with it, like putting the content of a form into an e-mail message, or turning the data into a database query.
You can often see that a CGI program is being used by seeing “cgi-bin” in a URL, but not always.
CGI
The common gateway interface is a specification that allows data to be passed back and forth between a Web server and a user visiting a site. CGI applications can be written in languages such as C, C++, Java and PERL. Webmonkey’s CGI Scripts for Fun and Profit will give you an idea of how to write your own.
cgi-bin
The most common name of a directory on a web server in which CGI programs are stored.
The “bin” part of “cgi-bin” is a shorthand version of “binary”, because once upon a time, most programs were refered to as “binaries”. In real life, most programs found in cgi-bin directories are text files -- scripts that are executed by binaries located elsewhere on the same machine.
channel
Virtual area where Internet Relay Chat (IRC) users communicate in real time. There are thousands of channels located on the Internet.
Channels
Channels are the way in which push media deliver content. In Netscape's Netcaster, content can be brought onscreen without reloading the page or redrawing the whole screen. One interesting feature of the layer tag is the ability to change the source dynamically. For example, the Wired News section of the HotWired channel keeps one layer filled with the latest Wired News summary and reserves another for loading any story selected by the user.
Chat Room
A place on the Internet where people go to "chat" with other people in the room. Actually there are thousands of these Chat Rooms. The rooms are usually organized by topic. For example in a Michigan Room you would expect that most of the participants in the room are probably from Michigan or a Gay room, where the participants are usually gay. When you're in a Chat Room you can view all of the conversations taking place at once on your screen. Liberal use is made of aconyms in these rooms so you may want to study up or keep a cheat sheet with you at first. You can also get into a private chat room where only you and one or two others may talk. This can be an inexpensive way to keep up with friends and relatives who are online.
Chocolate
A crucial computer term. Chocolate is what you eat when you get frustrated with web functions such as searching for specific items, writing web pages, or just being a Newbie
Churn
Churn refers to what happens when a user leaves a service, and "service" in this case can describe almost anything from a dialup ISP account to a listserv subscription. Churn is the major concern of almost any e-business, if only because it's so hard to attract users in the first place. Most sites, therefore, have tried to develop "sticky" services to keep us coming back, or encourage us to give them basic pieces of information so they can keep in touch with us.
CIX
Commercial Internet Exchange) A pact between network providers that allows them to do accounting for commercial traffic.
click stream
The path a visitor follows through a given web site (from page to page to page). See also user session.
Clickthrough
Clickthrough is the rate at which viewers actually click on ad banners and go to the advertiser's site - whether to sign up for something, to make a purchase, or just to find out more. It generally ranges from 1 to 3 percent industry-wide, a calculation arrived at by dividing the gross number of clicks by the gross number of advertising impressions served for a given campaign. The best clickthrough we ever achieved on a campaign was 20 percent, possibly because our banners simulated JavaScript error alert boxes. (No one will ever accuse us of taking the highbrow approach.)
Client
A software program that is used to contact and obtain data from a Server software program on another computer, often across a great distance. Each Client program is designed to work with one or more specific kinds of Server programs, and each Server requires a specific kind of Client. A Web Browser is a specific kind of Client.
Client
The browser (see above) used by a visitor to a Web site.
Client Errors
Percentage of visitors who click on a viewed advertisement. This is a good indication of the effectiveness of this ad.
CLUT File
In computer graphics, a color look-up table, or CLUT, is the set of available colors for a given application. For example, a 24-bit system can display 16 million unique colors, but a given program would use only 256 of them at a time if the display is in 256-color mode. The CLUT in this case would consist of the 16 million colors, but the program's palette would contain only the 256-color subset. To avoid dithering (i.e., varying the pattern of dots in an image) on 8-bit machines, you should only use colors from a predesignated CLUT.
CMYK
CMYK stands for cyan magenta yellow and blacK and is a color system used in the offset printing of full-color documents. Offset uses cyan, magenta, yellow, and black inks and is often referred to as "four-color" printing. Monitors use red, green, and blue light instead, so they display images using a different color system called RGB. One of the great problems of the digital age has been matching colors between these two systems; i.e., taking a digital RGB image and making it look the same in print using CMYK. These problems are addressed by applications such as the Pantone Matching System (PMS).
COM
Microsoft's component object model allows programmers to create objects (programs) that can run from any Windows desktop environment. The basic architecture of the model defines the interfaces of the objects and different ways that they can be executed. COM allows objects to be created in almost any programming language and affords the programmer the ability to incorporate a set of third-party controls such as OLE and ActiveX. The COM+ standard introduced improvements to the original model.
COM port
Communications Port). A plug-in socket in back of the computer for hooking up devices such as modems.
communications software
Also referred to as telecommunications software, this software allows one computer to connect with other computers across telephone lines (via modems) and share information. Communications software transmits instructions to your modem that directs it to make connections, transfer files, and carry out other procedures.
Company Databases
The database installed and used by WebTrends to look up the company name, city, state and country corresponding to a specific domain name.
connect time
The period during which a user is signed on, usually for a fee, to an online service, bulletin board system, host computer, or Internet service provider.
Cookies
The most common meaning of “Cookie” on the Internet refers to a piece of information sent by a Web Server to a Web Browser that the Browser software is expected to save and to send back to the Server whenever the browser makes additional requests from the Server.
Depending on the type of Cookie used, and the Browser’s settings, the Browser may accept or not accept the Cookie, and may save the Cookie for either a short time or a long time.
Cookies might contain information such as login or registration information, online “shopping cart” information, user preferences, etc.
When a Server receives a request from a Browser that includes a Cookie, the Server is able to use the information stored in the Cookie. For example, the Server might customize what is sent back to the user, or keep a log of particular user’s requests.
Cookies are usually set to expire after a predetermined amount of time and are usually saved in memory until the Browser software is closed down, at which time they may be saved to disk if their “expire time” has not been reached.
Cookies do not read your hard drive and send your life story to the CIA, but they can be used to gather more information about a user than would be possible without them.
Cookies
Persistent Client-State HTTP Cookies are files containing information about visitors to a web site (e.g., user name and preferences). This information is provided by the visitor during the first visit to a Web server. The server records this information in a text file and stores this file on the visitor's hard drive. When the visitor accesses the same web site again, the server looks for the cookie and configures itself based on the information provided.
CoSN
(Consortium of School Networks) A nonprofit group whose members include K-12 teachers, hardware and software vendors, and Internet Service Providers (ISPs).
CPC
Rather than paying a flat rate to run an ad on a site, sometimes advertisers will pay only for the number of clickthroughs, or cost-per-click (CPC), they derive from the ad. While it's popular with advertisers, CPC payment is frowned upon by most Web sites and by the IAB.
After all, banners serve a larger purpose than just getting people to click. Like advertising in other media, banners help raise general brand awareness and familiarity with a product. While only 1 to 2 percent of users actually click on banner ads, a much larger percentage will gain an overall familiarity with the product or brand. CPC buys ignore this value altogether, giving advertisers a mighty good deal.
CPM
CPM, or cost per thousand impressions, is the marketing world's metric for judging the merits of different media buys. Offline, CPM is calculated by taking the total cost of a given ad buy, dividing it by the total estimated viewership of a given advertisement, and multiplying the total by 1000. Here's an example: You buy a magazine ad for US $5,000. The magazine's subscriber base is 50,000. Therefore, the CPM will be ($5,000/50,000) x 1,000, or $100.
On the Web, CPM is a little different. Since it's so difficult to accurately determine the total number of visitors to a Web site, the CPM is calculated using the number of actual ads served. The distinction is subtle, but critically important: in the offline world, marketers simply guess how many times an ad is seen, whereas on the Web, we know.
Cracker
A number on many web pages that will count the number of hits or count the number of times the page has been accessed. Basically, it counts the number of people that have visited that page.
Cracker
A person who breaks into a site through a computer's security. While Basically the same thing as a "Hacker", a Cracker is sometimes considered to be more malicious and destructive.
CRC
(cyclic redundancy check) An error-checking procedure for data transmission. The sending device performs a complex calculation, generating a number based upon the data being transmitted, and sends that number to the receiving device. The receiving device performs the same calculation after transmission. If the results match, the transmission succeeds. If the numbers don't match, it means the message was received in an altered state, and the data may be incorrect.
Creative
Advertising people are funny. They call magazines "books," television "broadcast," and advertisements "creative." While the idea of calling ads "creative" may vary from ludicrously hopeful to woefully inadequate, when someone from the advertising world tells you they've been doing some great creative lately, what they really mean is "ads."
CRM
(Customer Relationship Management) Term used to describe the sophisticated personalization tools some vendors are developing to help define customer groups and target them with the right products and services. Companies use web-based CRM products to help answer the question, "Who are my most profitable customers on the Web, and how do I target them more effectively?"
Crop
To crop means to cut the pieces of an image that you don't need. Cropping differs from resizing because when you crop an image you retain the dimensions of the image. Resizing an image actually shrinks the image into smaller dimensions.
Cryptography
The basis for many types of secure transmission over the Internet, cryptography is a constantly changing and evolving field of mathematics that on the Internet refers to the practice of encrypting data for safe transmission. Regular data is coded into a cipher (which looks like scrambled text) then transmitted and deciphered by the receiving party.
CSS
allow you to define how Web page elements are displayed. Specific margins or colors can be associated with headers and links, for example. When style sheets are applied to a new page, the elements are changed according to the specifications of the style.
Cyberpunk
Cyberpunk was originally a cultural sub-genre of science fiction taking place in a not-so-distant, dystopian, over-industrialized society. The term grew out of the work of William Gibson and Bruce Sterling and has evolved into a cultural label encompassing many different kinds of human, machine, and punk attitudes. It includes clothing and lifestyle choices as well.
Cyberspace
Term originated by author William Gibson in his novel Neuromancer the word Cyberspace is currently used to describe the whole range of information resources available through computer networks.
Cyberspace
Term used to describe the Internet; the term was coined by science-fiction novelist William Gibson in 1984 in Neuromancer.
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