What Are Search Engines?

Search Engines are interactive web sites which help to find your interests web sites from Internet. Search engines have their own rules & ways for search sites. Lot of search engines handle own giant database about web sites. They have text box which you can enter your search topic then they give result with web site title, short description & it's URL. They have spiders or crawler (or robots or worms or trawlers) which is software program, which can go into one site then follow it's links and index about that site in their database. Search engine use Submit Your Site link to know about new sites. So if one site have links to other web site, then spider go into that site also. Normally spider visit all sites which include their database once a month to verify that site is updated or changed. After spidered or crawled, search engine take copy of every page which was spidered. it is called indexed. But to indexed it will take one week to six months. Therefore site which is spidered will not indexed in their database. Some search engines use InkTomi database for there search  while other do combine search with other search engines for results ( as Dogpile). But all search engine's search results are not same cause they have their own search logic. Look : Yahoo! & AltaVista.
 
 Example Search engine results :

  How search engines categorize & rank web sites

1. According to subject category - Yahoo, Excite, Lycos, etc
2. Spidered copy : use every words of every web pages in site - Google, Altavista, HotBot, etc
3. According to meta tags : Title, Description, Document & Keywords - Dogpile, Mamma, C4, etc
4. Ranking site with visitors hitting in search results - PlanetCleck, Magellan, etc
5. Number of links to outer sites in particular site - Excite
6. Update speed : Days, Weeks or  Months - WebRing, Lycos, Dmoz, etc
7. Web personality or technical features of web sites - Looksmart, Yahoo!, etc
8. People's or Company details - White pages & Yellow pages

  Search engine types

1. Spider Searchers - use spider for copy whole web site into their databases (as Google)
2. Web guiders - web site organize by subject section (as Yahoo!)
3. Meta Searchers - use site's meta tags for index in other search engine's databases (as Dogpile)
4. White pages - categorize people's emails, addresses and personal details (WhoWhere)
5. Portals - give one country's or world's daily basis information as news, weather, stocks, sports, etc (as Exicte)
6. Gateways - handle links to other web sites without particular topic (subclass of portal)
7. Rings - Use circle linking system among sites of same category or subjects (webcam WebRing)
8. Directories - handle links with particular section or subjects ( as E-Sangha on Buddhism)
9. Yellow pages - categorize business's emails, addresses and company details
10. Subject Wise - Crawel the web according to particular subject or only one topic (medscape.com)

  Which Search Engine Is Good When?

• Need information has been published in past years back - Try HotBot
• Need check particular URL is available - Use Google
• Want to find lot of information in certain topic in same web page - Use Alta Vista with NEAR keyword
• Want to find web page witch no longer exit - Try in Google cache
• Need to find certain event that goes with time line - Use Vivisimo
• Help to school children for find information with school project - Use Yahoo!
• Remember Yahoo! is like library, so if you want search about educational topic use Yahoo!

              So if you need quick finding about particular subject which is not certain focus ( as Astronomy)  don't use spider searchers. Use other  type of search engines. If you need to know about certain things, place or topic ( as Australia) use only spider searchers. Read FAQ page in every search engines before search. Use meta search engines instead of main search engines cause they have best selection ways such as give only top 10 web sites on major search engines, combine more than two search engines ( eg.. Info has 14 search engines, etc)
   
Doing advanced searching

• Quotes ('') - words must be include in order in search results. Ex : 'lanka' 'economic' 'stock' will give results about stock information in economic web sites in Sri Lanka.
• Plus (+) or AND - words must be include without order in search results. Ex : astrology +Indian +China will give results sites have details about Astrology about India and China.
• Minus (-) or NOT - words must not include in search results. Ex : culture -music -dance will give results cultural web pages which are not include music and dance.
• OR - search multiple words in different topics. Ex : penpal OR love OR history will give results all pages have words penpal, love and histroy.
• NEAR - search terms with near relationship between two words,  in same sentence, or paragraph in same document. Ex.. government NEAR policy will search policy of the government
• ADJ - use to search about topic. Here first word is main topic and sub words about main topic.  Ex.. china ADJ government will search document about china.
• SAME / WITH used to search words in same sentence or paragraph.
• Asterisk (*) - words begin & end with some multiple characters. Ex : com* will give topic related to computer, company, commnucation. You must need four begin characters.
• Percent (%) - words begin & end between one character hidden. Ex : ga%l will give topic related to gaol, gael, gall,etc. Some search engines there have no different between * and %.
• Except Quote other search literals can't use with one word. Ex : Wrong +dog, -cat, OR culture
• You can use mixing these search literals. Ex : Lanka +music -dance OR India
• Always try to construct your own search phrases with combining in advance search keywords.