To navigate through this vast amount of information is difficult and to find relevant information can seem an impossible task. In practice, search engines can return tens of thousands of hits to a query of which the majority of hits may be irrelevant. The most relevant hits may not always be displayed within the first ten hits, even though the results are theoretically ranked in order of relevance to the query.
Search engines use ranking algorithms to organise hits in order of relevance to a query.
The location of a term within a page can also affect the ranking. For example, a page that has a query term in its title or meta tag field may receive a higher rank than a page that has the query term in just its body. This technique, however, has a number of problems. It assumes that a user knows what words have been used in pages that are relevant to their query. Keywords can also be ambiguous because they can have more than one meaning when they are out of context.