The deep web (or invisible web or hidden web) is the name given to the publicly accessible pages on the World Wide Web that are not indexed by search engines. It consists mainly of dynamically generated pages that are based on responses to database queries. It should not be confused with the term dark web or Dark internet which refers to machines or clusters of machines unreachable by other computers on the internet.

Search engines use web crawlers that follow hyperlinks. Such crawlers typically do not submit queries to databases due to the potential infinitude of queries that can be made to a single database.

It has been noted that this can be (partially) overcome by having links to query results, thus increasing Google-style PageRank results for a theoretical member of the deep web.

In a 2000 study by the search company BrightPlanet, the inaccessible part of the web was estimated to be about 500 times larger, in terms of number of documents, than what search engines already provide access to. Any such figures must be taken with caution, however, due to the difficulty of distinguishing between genuinely different documents and documents that merely represent different database views of the same content.

References

• Gary Price & Chris Sherman. The Invisible Web : Uncovering Information Sources Search Engines Can't See. CyberAge Books, July 2001. ISBN 091096551X

External links

• http://library.albany.edu/internet/deepweb.html
• http://www.invisible-web.net/
• BrightPlanet - Deep Web White Paper

Related Research

• QProber: Classifying and Searching "Hidden-Web" Databases
• MetaQuerier: Exploring and Integrating the Deep Web