Algorithm. A set of rules that a search engine uses to rank the pages contained within its index in response to a particular query. No search engine reveals exactly how its algorithm works, to protect itself both from competitors and from those who wish to spam the search engine.
Back links. These are links to a website from external sources, including other web pages, directories, and advertising.
Banned. When pages are removed from a search engine’s index because the search engine has deemed them to be spamming, or violating one of the search engines other rules.
Click-through rate. How many people clicked on a link, as a percentage of the total number of people that saw the link.
Cloaking. The act of serving content to search engine spiders that is different to what normal visitors would see. Search engines will ban you if they find you doing this.
Contextual links. Contextual links are displayed on web pages when the content on the page indicates to an ad server that the page is a good match for specific keywords or phrases.
Conversion rate. The percentage of visitors to a website who buy something.
Cost per click...