How Different form of Engines like google

Different type of Search engines:

Spider search engines:
Search engines compile their databases using "spiders" or "robots" ("also called bots") to crawl through web space coming from url to website link, discovering and also looking into web pages.

Directory search engines:
Inside contrast to spider search search engines, directories are not automatically generated but are authored by writers. An online site which is published to any index will be eventually catalogued and also related to one or more matters. As the directories are set up by experienced writers, they typically generate a lot more focused final results. Illustration will be Bing!

Hybrid engines like google:
Several search engines today combine a spider engine together with a directory program. The directory typically includes web pages who have been recently evaluated and also used.

FFA databases (Free of charge for many Back links):
Free-for-all website link lists are pages in which links to web site can be entered together with a short comment. Owners of web sites thereby enter the registration themselves, and there is no editing board to review the entries, it is free and become immediately effective. Promoting web site to FFAL is not very unpopular because of poor quality directory listings.

Pay Per Inclusion Engine:
Advertiser needs to pay a fee to search engines in order to get their web sites to be listed in the search engines. Yahoo!, LookSmart, etc. are these kind of Engines. Normally, your web site will be indexed by the search engines within 24 hours and your listing will be updated frequently. You are also requested to pay a renewal fee for your listing every 6 months or annually. However, this doesn't guarantee a particular position in the search results, you still need to optimize your web site manually in order to achieve higher ranking.

Pay-Per-Click search engines:
A Pay-Per-Click (also known as Pay-Per-Ranking, Pay-Per-Placement or Pay-Per-Position) search engine enables you to list your site at the top of the search results according to the keyword bid. Examples are Overture.com, 7Search.com, FindWhat.com etc.

Meta:
Metasearchers or Metacrawlers do not compile sources. As an alternative, they will lookup the particular sources regarding multiple sets of individual engines at the same time, for example Dogpile, MetaCrawler, Mamma and so forth.