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About Search Engines

Posted On 17 Sep, 2007Views : 3411 Previous | Next 
Search Engine

A search Engine is a system to retrieve information available on web. It works as a librarian who gives you all the books available on a particular topic in the library; In the same way, Search engine gives you all the information available on the web on a particular topic asked by you. Generally all the systems available on internet to retrieve information on web is known as Search Engines but actually there are three different types of Search Engines i.e.

  • Search Engines
  • Directories
  • Portals

Search Engine (crawl-based)

The search system which are crawl based and who create their listing automatically by crawling the web are known as Search Engines. Page titles, body copy and changes in web pages and other elements all play a role in listing. There are three types of search engines i.e.

  • Tier I Engines
  • Tier II Engines
  • Tier III Engines

 

Tier I Search Engines

Top search engines that serve the vast majority of searcher queries.

They are also known as Major Engines, Top Tier Engines or GYM (Google, Yahoo! and Microsoft Live Search).


Tier II Search Engines
Smaller, vertical and specialized engines, including general engines, such as Ask.com and AOL; meta-engines that search and display results from other search engines, such as Dogpile; local engines, shopping and comparison engines, and business vertical engines. Tier II Search Engines don’t offer the search query market share or features of the Tier I engines; however, Tier II engines can target specific, niche markets and are usually lower cost.

Tier III Search Engines
Contextual distribution networks, through which marketers’ ads appear on pages within the PPC engine’s content network, triggered by user web site page views at the moment that contain the advertiser’s keyword in its content. Cost is usually through Cost-Per-Thousand-Impressions (CPM) charges, rather than Pay Per Click (PPC).


Directories (human-powered)

The search system which is human-powered are known as Directories in which editors play an important role; either site owner or editor himself write a short description about the site and then submitted to the directory. When a visitor searches some thing, then directory shows only that information which is submitted. Changes in web page has no effect on listing.
Some Search Systems use both strategies i.e crawl based and human based that systems are known as Hybrid System.

Major web directories are : dmoz.org , Yahoo Directory


Portals
A Portal is a site on the world wide web that provide information from diverse sources in a unified way. Besides working as a Search Engine, it also provide services like news, stock prices, infotainment and many more…. Personal Portals provide personalized information. Beside this there are Regional Portals, Government Portals, Corporate Portals, Hosted Portals, Domain Specific Portals etc. Entertainment, Environment, Investment, Shopping or on any feature a portal is available on internet which provide vast information to the internet users. Portals actually deliver the search results from one of the other search engines or directories e.g. AOL, Netscape, CompuServe, iWon, and many more get results from Google. Lycos gets its results from AllTheWeb.

AskJeeves gets its results from Teoma. HotBot, Excite, and WebCrawler get results from Overture, the pay-per-click search engine.


Related articles
History of Search Engine
How search engine works


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