Searchengine Classification – Part 3 – Hybrid Search Engines

Yesterday we discussed the directories like dmoz.org that are edited and maintained by humans.

Today we shall go deeper into the hybrid and meta search engines.

Here are the four major search engines types again:

1) crawler based search engines.
2) directories (edited and maintained by humans)
3) hybrid engines (META engines and engines using other engines’ results)
4) paid inclusion engines and pay-per-performance

Hybrid search engines (META engines and search engines using other engines’ results)

As directories use human editors to index websites and crawler based search engines use crawlers to index websites, hybrid search engines use both humans and crawlers to index a website.

Hybrid search engines combine a directory with a search engine to give their visitors the most relevant and complete results.

Both Google.com and Yahoo.com are hybrid search engines. Yahoo! has the tendency to be a human powered directory and Google has the tendency to be a crawler based search engine.
As a rule, a hybrid search engine will favor one type of indexing over another.

In a nutshell:
• Search engines use crawlers
• Directories are edited and maintained by humans
• Top search engines use both crawlers and humans

Today the top ten search sites are hybrids. For example, Yahoo! started out as a directory, but now it gets additional data from Google’s search results. On the other hand, Google uses Open Directory Project's directory to enrich its listings.

What is a Meta search engine?

Meta search engines also referred to as multi-engines, parallel search engines, multi threaded search engines or mega search engines combine the results from a number of search engines and directories at the same time and lay them out in a results page and present them to the user. It does not create its own database however.

Meta search engines are very useful when you want a small number of relevant results and want to see the most important hits of each individual search engine. You can also select which search engines to search.

A setback of meta search engines is that you can only use simple queries. If you’d use advanced query techniques some of the underlying search engines will not understand your query.
Examples of meta search engines are MetaCrawler, DogPile, Vivisimo, C4, Mamma, Pro fusion, Search, Surfwax, Unabot and LemmeFind.

Tomorrow:
Paid inclusion engines and pay-per-performance engines