Algorithm

An algorithm is a mathematical formula used by search engines to determine rankings. The three major algorithms associated with Google, Yahoo! and Bing put the most weight on two main factors:

Content Relevancy

Web site results need to match a user's query as accurately as possible. The search engine algorithm analyzes content and keyword relevancy and gives a web page a score. Better scores mean a page is more likely to rank near the top for applicable searches.

Some types of content are not able to be read by search engine spiders and therefore won't get analyzed by the algorithm. JavaScript and secure server data, as well as text embedded in images and Java applets, are invisible to search engines.

Google recently announced that by using Adobe's searchable SWF library they have been able to index far more text content in Flash than ever before.

Link Popularity

PageRank is the most widely known algorithm, as it has been discussed extensively by webmasters for years as well as included in the Google Toolbar, a web browser add-on. PageRank, as well as other link algorithms, looks at the quality and quantity of links a web page receives from other sites, as well as pages on its own domain. External link factors are weighted more heavily than internal, and the anchor text plays a big part in determining how valuable the link is.