Cache: refers to the memory area which stores copies of web pages on your PC that make it easier for you to open up a website. Google allows its users to access cached pages of listed website.

Click-through Rate: is the rate at which visitors on a search engine click on search listing or banner ads. The click-through rate for search listings is far higher than that for banner ads.

Cloaking: is the process by which websites provide spiders keyword rich content so as to assure a good search listing. However the audience is not shown this data and in contrast finds useless and irrelevant information.

Conversion Rate: is the actual rate at which visitors to the website become customers.

Cookie: is the information that is placed by a web server on a visitor's computer. It is accessed and retrieved once the web site is visited. Cookies are frequently used for user IDs, for e-mail addresses, etc.

Cost-Per-Action: As the phrase suggests it is the price charged for an action such as signing up for an e-zine, downloading trial software, entering a contest online, etc. It is an online advertising payment model.

Cost-per-click: or CPC is the charge that has to be paid to a search engine every time a visitor goes to your website by clicking on a link.

Cost per Thousand: is the price that is to be paid by the client to the search engine for a thousand click impressions. Impression means the number of times an ad or a banner is downloaded and is assumed to be seen by the visitors.

Crawler: is another term for search engine spiders that regularly search websites for data and information and store in the database.

Google Bombing: is when a group of websites mostly blogs link an unfavorable page to a company website in a manner that it ranks high on the Google search result.