Dear Rajashekaran, a. The Deep Web is nothing but the portion of the World Wide Web which has not been indexed by surface search engines such as Google due to technical reasons or due to limitations because of policy matters. Many specialized search tools/search engines exist for exploring the deep web. Once we have found the right search tool/engine, same search strategies can be employed as in the case of general search engines; but the hard part is to find the appropriate deep web search source. For information regarding using surface search engines to find deep web content please visit http://21cif.imsa.edu/tutorials/micro/mm/invisible/index_html?b_start:int=5. b. There is nothing that can be termed as the most popular and useful deep web search engine. There is no Google equivalent in the Deep Web. The index base of deep web search engines is limited and often restricted to specialized databases and other non-html formats such as PDF and PPTs. Further, it seems, the index of each deep web search engine is unique in its own way and therefore it is next to impossible to find a panacea for search problems when it comes to Deep Net. The way left is to identify the appropriate web source/search engine and do search there. For example, for health related information, one can take help of deep search engines such as mammahealth (www.mammahealth.com/), closurelook (www.closerlooksearch.com/) or specialized health databases. However, the following deep web search engines can be tried: i. Direct Search: http://www.freepint.com/gary/direct.htm ii. CompletePlanet http:// www.completeplanet.com iii. Turbo 10: http://turbo10.com iv. Incywincy: http://www.incywincy.com/ A list of such tools/engines can be found at www.trinity.wa.edu.au/plduffyrc/web/invis/invisible.htm Nothing definite can be told about the popularity of deep web search engines because the existence of deep web itself is not known to the majority of the Internet users. c. http://www.llrx.com/features/deepweb.htm and deepwebresearch.blogspot.com/ offer a rich source of links to deep web related topics. The links lead to highly informative sources and cover the best that is available on the WWW about the deep web. Kumar Patil,Belgaum -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.