The Relevance and Popularity of Web Pages
Relevance
This can be defined as the degree to which the web pages returned from a search match the searcher’s search term and intention. Search engines consider a page to be relevant if the phrase used by the searcher shows up several times throughout the page and occurs in the page title or important headlines or subheaders within the page itself and in the pages meta data.
Search engines also take into account other pages on the web site to see if those pages are displaying content that is related in some way to the page selected i.e. the search engine is looking to see if the website has a particular theme.
Popularity
The popularity of a given web page or web site is measured by the number and quality of the inbound links to that page. Search engines look at which site is linking to a page, i.e. the authority of the linking site (e.g. .edu and .gov sites) and they also count what is being said within and around the link
The above is a gross oversimplification of the process. Today, search engines, use extremely complicated and far reaching algorithms to determin who gets to the top listing for a given search term. The days of fooling the search engine by keyword stuffing and other forms of spamming are over.