C

Campaign: The advertising and promotion done during a given period of time.

Catch-all: A program that allows any email sent to your domain to go to a particular email address. That allows any email sent to a misspelled or unused username will still get to a person who can deal with them.

CGI script: A program, often written in the PERL programming language, written to run on any computer. They add value to a website by doing any number of cute things. For example, a CGI script can send a visitor to a "thank you" page when they submit a form. They normally go in a separate folder from your HTML files.

Click through rate: The percentage of users who click on a viewed advertisement. It shows how effective the ad is, when compared to the average rate of the media.

Client: The browser used by a visitor to a website.

Client errors: An error occurring due to a bad request by the visitor's browser, such as typing in a page name that doesn't exist. Client errors will show error numbers in the 400 range in your log analysis program.

.com: Suffix indicating a commercial domain.

Comment tag: An HTML tag. <!-- Your Comment Here --> It is invisible to your website visitors, but many search engine spiders index them. Use them to mark parts of your page for future revision, as another place to put your site description, and possibly another place to list keywords.

Cookies: These aren't the kind your Grandma used to make! Web cookies are files containing information about visitors to a website, like username, password, and what they want to buy. It is stored on the visitor's computer, and sent back to the website that created it when the visitor comes back or gets to the order page. Cookies can also retrieve information like monitor resolution and platform to webmasters who intend to use this information to improve their website.

core product: The product a business is built around. For instance, McDonald's core product is the Big Mac.

Counter: A CGI script which counts the number of times your page is requested by visitors. Remember that a visitor which visits your page more than once will be counted every time.

CPA: Cost per action for banner ads. This is the best type of rate to pay for banner advertisements, and the worst type of rate to charge. Advertisers only pay for the visitors who click on their banner and then sign up, fill out a form, or purchase something on their website. This is most common for Affiliate Programs. My opinion is this type of payment arrangement is already an endangered species, and will soon become extinct.

CPC: Cost per click through for banner ads. The advertiser only pays when a visitor clicks on their banner (whether or not the visitor waits for their page to load before leaving). Look for this type of rate when you plan to place a banner on a website with related content.

CPM: Cost per thousand (impressions or subscribers). CPM is a marketing term you will see often when researching banner and magazine ad rates. It helps you determine how much you are spending per person viewing your ad, and the company by allowing them to charge more as their subscriber base or hit count increases without changing their posted ad rates. If you are planning to offer advertising, this is the way to do it.

Cracker: A person who breaks into copyrighted software to illegally duplicate it or remote computers to destroy information.

CSS: Cascading Style Sheets. They let you assign the look of different elements of each webpage in your website. They're an HTML 4.0 feature, so older browsers may not support them.

Cyberspace: The Internet. The phrase was coined in 1984 by William Gibson in his book, Neuromancer.