Algorithm. A set of rules that a search engine uses to rank the pages contained within its index in response to aparticular 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 externalsources, including other web pages, directories, and advertising.
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 enginespiders 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 adserver 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 (CPC). A system where an advertiser pays an agreed amount for each click someone makes on a link leading to their website.
Directories. A type of search engine where listings aregathered by humans, rather than by automated web crawlers.
Graphical inventory. Banners and other ads that appeardepending on the keywords a page contains. This includes pop-ups, browser toolbars and rich media.
Index. The collection of information a search engine has that searchers can query.
Landing page. The web page that a visitor reaches after clicking your search engine listing.
Link. A link is text that you can click on to go to another website, or another page on the same website.
Listings. The information that appears on a search engines results page in response to a search.
Meta-search engine. A search engine that returns listingsfrom two or more other search engines, instead of using its own index.
Meta description tag. This meta tag allows pages to provide descriptions to search engines.
Meta keywords tag. Allows authors to add text to a page to help with the search engine ranking process.
Meta robots tag. Allows page authors to keep some webpages from being indexed by search engines. Similar to a robots.txt file.
Natural listings. The listings that search engines do not sell. Instead, sites appear solely because a search enginebelieves it is important for them to be included, regardless of payment. Note that paid inclusion listings are still treated as natural listings by many search engines.
Outbound links. Links on one website that lead to other websites.
Paid inclusion. An advertising program where pages are guaranteed to be spidered and included in a search engines index in exchange for payment.
Paid listings. Listings that search engines sell toadvertisers, usually through paid placement or paid inclusion programs.
Pay-for-performance. A term popularized by some search engines as a synonym for pay-per-click. It stresses to advertisers that they are only paying for ads that "perform" in terms of delivering traffic, as opposed to CPM-based ads, where ads cost money even if no-one clicks on them.
Paid placement. An advertising program where listingsappear in response to particular search terms, with higher rankings typically obtained by paying more than other advertisers.
Rank. The order in which web pages are listed in search engine results.
Results page. The page that appears after a user enters their search terms.
Robots.txt. A file used to keep web pages from being indexed by search engines.
Search engine. A service designed to allow users to search the web, or another database of information.
Search engine optimization (SEO). Altering a website so that it ranks higher in the search engines.
Search terms. The words a searcher enters into a search engines search box.
Shopping search. Shopping search engines allow shoppers to search the web for products and their prices.
Spam. Any search engine marketing method that a search engine decides is detrimental to its efforts to deliver relevant search results.