Optimize My Web Site Dictionary

Cache - Copy of a web page stored by a search engine. When you search the web you are not actively searching the whole web, but are searching files in the search engine index. Some search engines provide links to cached versions of pages in their search results, and allow you to strip some of the formatting from cached copies of pages.

Calacanis, Jason - Founder of Weblogs, Inc. Also pushed AOL to turn Netscape into a Digg clone. Jason's blog, Calacanis.com

Canonical URL - Many content management systems are configured with errors which cause duplicate or exceptionally similar content to get indexed under multiple URLs. Many webmasters use inconsistent link structures throughout their site that cause the exact same content to get indexed under multiple URLs. The canonical version of any URL is the single most authoritative version indexed by major search engines. Search engines typically use PageRank or a similar measure to determine which version of a URL is the canonical URL.
Webmasters should use consistent linking structures throughout their sites to ensure that they funnel the maximum amount of PageRank at the URLs they want indexed. When linking to the root level of a site or a folder index it is best to end the link location at a / instead of placing the index.html or default.asp filename in the URL.
Examples of URLs which may contain the same information in spite of being at different web addresses:

Catch All Listing - A listing used by pay per click search engines to monetize long tail terms that are not yet targeted by marketers. This technique may be valuable if you have very competitive key words, but is not ideal since most major search engines have editorial guidelines that prevent bulk untargeted advertising, and most of the places that allow catch all listings have low traffic quality. Catch all listings may be an attractive idea on theme specific search engines and directories though, as they are already pre qualified clicks.

Click-Through - The action of clicking on a link to visit a web page.

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).

Example:

A link is displayed 20 times (20 impressions) and clicked on 2 times.
The CTR is 10% (2/200=0.10).

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.

Note: Cloaking is discouraged by most major search engines, including Google.

Co-citation - In topical authority based search algorithms links which appear near one another on a page may be deemed to be related to one another. In algorithms like latent semantic indexing words which appear near one another often are frequently deemed to be related.

CGI - Common Gateway Interface - interface software between a web server and other machines or software running on that server. Many cgi programs are used to add interactivity to a web site.

Client - A program, computer, or process which makes information requests to another computer, process, or program.

Cloaking - Displaying different content to search engines and searchers. Depending on the intent of the display discrepancy and the strength of the brand of the person / company cloaking it may be considered reasonable or it may get a site banned from a search engine.
Cloaking has many legitimate uses which are within search guidelines. For example, changing user experience based on location is common on many popular websites.

Cluetrain Manifesto, The - Book about how the web is a marketplace, and how it is different from traditional offline business.

Clustering - In search results the listings from any individual site are typically limited to a certain number and grouped together to make the search results appear neat and organized and to ensure diversity amongst the top ranked results. Clustering can also refer to a technique which allows search engines to group hubs and authorities on a specific topic together to further enhance their value by showing their relationships.

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.

Example:

<!--Comment-->

Comments - Many blogs and other content management systems allow readers to leave user feedback.
Leaving enlightening and thoughtful comments on someone else's related website is one way to help get them to notice you.

Compacted Information - Information which is generally and widely associated with a product. For example, most published books have an ISBN.
As the number of product databases online increases and duplicate content filters are forced to get more aggressive the keys to getting your information indexed are to have a site with enough authority to be considered the most important document on that topic, or to have enough non compacted information (for example, user reviews) on your product level pages to make them be seen as unique documents.

CMS - Content Management System. Tool used to help make it easy to update and add information to a website.
Blog software programs are some of the most popular content management systems currently used on the web. Many content management systems have errors associated with them which make it hard for search engines to index content due to issues such as duplicate content.

Concept Search - A search which attempts to conceptually match results with the query, not necessarily with those words, rather their concept.
For example, if a search engine understands a phrase to be related to another word or phrase it may return results relevant to that other word or phrase even if the words you searched for are not directly associated with a result. In addition, some search engines will place various types of vertical search results at the top of the search results based on implied query related intent or prior search patterns by you or other searchers.

Conceptual Links - Links which search engines attempt to understand beyond just the words in them. Some rather advanced search engines are attempting to find out the concept links versus just matching the words of the text to that specific word set. Some search algorithms may even look at co-citation and words near the link instead of just focusing on anchor text.

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.

Contextual Advertising - Advertising programs which generate relevant advertisements based on the content of a webpage.

Conversion - Many forms of online advertising are easy to track. A conversion is reached when a desired goal is completed.
Most offline ads have generally been much harder to track than online ads. Some marketers use custom phone numbers or coupon codes to tie offline activity to online marketing.
Here are a few common example desired goals

Bid management, affiliate tracking, and analytics programs make it easy to track conversion sources.

Cookie - Small data file written to a user's local machine to track them. Cookies are used to help websites customize your user experience and help affiliate program managers track conversions.

Copyright - The legal rights to publish and reproduce a particular piece of work.

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.

CPA - Cost per action. The effectiveness of many other forms of online advertising have their effectiveness measured on a cost per action basis. Many affiliate marketing programs and contextual ads are structured on a cost per action basis. An action may be anything from an ad click, to filling out a lead form, to buying a product.

CPC - Cost per click. Many search ads and contextually targeted ads are sold in auctions where the advertiser is charged a certain price per click. Examples of this include:

CPM - Cost per thousand ad impressions. Many people use CPM as a measure of how profitable a website is or has the potential of becoming.

Crawl Depth - How deeply a website is crawled and indexed. Since searches which are longer in nature tend to be more targeted in nature it is important to try to get most or all of a site indexed such that the deeper pages have the ability to rank for relevant long tail keywords. A large site needs adequate link equity to get deeply indexed. Another thing which may prevent a site from being fully indexed is duplicate content issues.

Crawl Frequency - How frequently a website is crawled. Sites which are well trusted or frequently updated may be crawled more frequently than sites with low trust scores and limited link authority. Sites with highly artificial link authority scores (ie: mostly low quality spammy links) or sites which are heavy in duplicate content or near duplicate content (such as affiliate feed sites) may be crawled less frequently than sites with unique content which are well integrated into the web.

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.

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 - Cascading Style Sheets is a method for adding styles to web documents.
Note: Using external CSS files makes it easy to change the design of many pages by editing a single file.
See also:

CTR - Clickthrough rate - the percentage of people who view click on an advertisement they viewed, which is a way to measure how relevant a traffic source or keyword is. Search ads typically have a higher clickthrough rate than traditional banner ads due to being highly relevant to implied searcher demand.

Cutts, Matt - Google's head of search quality.

Cybersquatting - Registering domains related to other trademarks or brands in an attempt to cash in on the value created by said trademark or brand.