Tuesday, September 30, 2008

search engines maintain their own database of webpage. You can type the keyword to be searched and the search engine returns liink to related web page from database. The database of web pages are maintained by programs called electronic spiders. some examples of search engines are as follows:
* www.google.com* www.altavista.com* www.searchcactus.com* www.infoseek.com* www.excite.com* www.nlseacrh.com* www.alltheweb.com* hotbot.lycos.com

Unlike a search engine,a meta-search engine does not have its own database. Instead, when you submit a keyword in the serach box,a meta-seacrh quickly and superficially visits several individual search engines at once.It does show by transmitting the keywordsimultaneously to various search engines, which search for the keyword in their own databases and return results to the meta-search engines.meta-searsh engine picks up only 10% of the result from any search engine.Each meta-search engine provides its own feature.Examples of meta-search engine are as follows.
*www.profusion.com: Allows you to search on nine search engines and allows you to select among them.It also allow you to select the "top 5" to accomplish your search.
*www.dogpile.com: one of the oldest and favored meta-search engine at a time .It searches 25 search engines. However,it searches only one search engine at a time. It also allows you to set the order engines to search.*www.askjeev.com: search six leading engines and itss own knowledgebase of six million answer.
*www.infind.com: search six engines in parallel and clusters the result after removing duplicate links. it can be configured to search additional engines.
*www.metacrawler.com: searhs nine engines and ranks results based on their relevance.
*www.savvysearch .com: sequentially searches 100 engines. you can select the search engines of your choice and specify the order of the search. you can also store the customized set of search engine for future use.
These are the directories maintained by individuals as againts the database that are maintained by electronic spiders in search engines. Individuals review and select sites for inclusion in their directories.The size of a subject drictories is much smaller compared to that of a search engine.These drictories are often orgaized into categories and subcatagoies ,depanding on the information they contian. Subject drictroies can be used for searchs of a more genreal nature and for information on popular topics,organization,commercial sites and products.however ,theymay not cantain the latest information,since they are updated manually.Examples of the subject dirtories are as follows.