SEO Glossary - Letter C
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.
CERT
Computer Emergency Response Team) A clearinghouse of information about network security.
Certificate Authority
An issuer of Security Certificates used in SSL connections.
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.
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.
Click-Through-Rate (CTR)
The number of times a link is clicked on divided by the number of times that same link is displayed (called an impression).
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.
Cloaking
Serving one version of a page to a human visitor and a different version of the same page to the search engines. This is usually done to "fool" the search engines into giving the page a higher rank than it would normally receive while making sure the human visitor sees a useful and attractive page.
Comment Tags
Used in a web page's HTML source code to indicate certain information about a section of the page code. Some search engines will consider keywords contained in comment tags for keyword density purposes, others (including Google) will not.
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.
Content
The information located on a web page. This includes text, images, and any other types of information that a webmaster places on the page.
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.
Counter
A script that counts the number of hits, unique visitors, and/or page views that a web page (or an entire site) receives. These "stats" provide very useful information for the webmaster
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 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.
Crawler
A program used by search engines to "crawl" the web by following links from page to page. This is how most search engines "find" the web pages that they place in their index. Also referred to as a spider or robot.
Crawling The Web
Search engines use crawlers to move from web page to web page by following the links on the pages. The pages "found" are then ranked using an algorithm and indexed into the search engine database.
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?"
Cross Linking
This is where the owner of two or more websites interlink the sites in order to boost their search engine rankings. If detected, cross linking often results in a search engine penalty.
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.
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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