As content of the World Wide Web (the Web) increases, users are finding it more difficult to search the content of the Web as well as experiencing problems merely navigating the content of the Web. Early methods of providing a user with an ability to search the content of the Web can be separated into two approaches.
The first approach involves the generation of an indexed database that is created based on the contents of web pages. This indexed database is created by automated search engines that systematically acquire web pages while searching for new and unique pages. This indexed database can then be searched using various query techniques. From these queries, references in the database can be presented to the user. The provided references are often ranked based on similarity to the form of the query.
In the second approach, web pages are fetched as mentioned above and are grouped into a categorical hierarchy, typically presented in tree format. The user then makes a series of selections while descending the hierarchy, with one or more choices at each level. These choices represent salient differences between the subtrees below the decision point. Several complexities are associated with the creation and usage of a categorical hierarchy. First, there are over one billion web pages making the manual categorization of such a volume of data prohibitively expensive. Second, the content of the web changes continuously. Because of those continuous changes, inconsistencies arise when attempting to re-access a page read on a prior occasion.