Types of Search Engines

Crawler Based Search Engines
Crawler-based search engines use software programs to find information on the Internet and store it for search results in massive databases or indexes. The programs used by the search engines are called ‘spiders’, ‘crawlers’, ‘robots’ or ‘bots’.

Examples of crawler-based search engines are: Google (http://www.google.com/)Ask Jeeves (http://www.ask.com/)

Human Powered Directories
These search engines (directories) depends upon humans for its listings. These human editors decide what category the site belongs to. They place the websites within specific categories in the directories database. These human editors comprehensively check the website and rank it depending upon the information they find, using a pre-defined set of rules.
There are two major directories at the time of writing:
* Yahoo Directory (http://www.yahoo.com/)
* Open Directory (http://www.dmoz.org/)

Hybrid Search Engines
Hybrid search engines are the combination of both crawler-based results and Human Powered directory results. These days more and more search engines are moving to a hybrid-based model. Examples of hybrid search engines are:
More and more search engines these days * Yahoo (http://www.yahoo.com/)
* Google (http://www.google.com/)

Meta Search Engines
Meta Search engines take the results from all the other search engines results, and combine them into one large listing. Examples of Meta search engines include:
* Metacrawler (http://www.metacrawler.com/)
* Dogpile (http://www.dogpile.com/)

Specialty search engines
Specialty search engines have been developed to cater for the demands of niche areas. There are many specialty search engines, including:
* Shopping
- Froogle (http://www.froogle.com/)
- Yahoo Shopping (http://www.shopping.yahoo.com/)
- BizRate (http://www.bizrate.com/)
- PriceGrabber (http://www.pricegrabber.com/)
- PriceSpy (http://www.pricespy.co.nz/)
* Local Search
- NZPages (http://www.nzpages.co.nz/)
- SearchNZ (http://www.searchnz.co.nz/)
- NZS (http://www.nzs.com/)
* Domain Name Search
- iServe (http://www.iserve.co.nz/)
- Freeparking (http://www.freeparking.co.nz/)