General Search Engine

The 10 top search engines combined index and access less than 50% of the World Wide Web. And yet, they remain the most efficient way to retrieve information for terminology and vocabulary (“keyword”) searching. The following is a list of 5 popular English language search engines.

The advantage of these types of search engines is that they can produce a large number of results with a diverse range of perspective.

The disadvantage of these types of search engines is twofold: (1) A large number of results are time consuming to manage and review; (2) The results will include a large number of things having nothing to do with scientific literature.

Google
Google uses an evaluation system that assesses websites and other Internet documents on the basis of the number of links from other sites to those documents. This technique is called PageRanking. PageRank looks at the linked sites and investigates how many of them link back. Thus, Google presents the mainstream, the more prevalent, and therefore usually the more reliable sites on a particular subject. You are not likely to come across personal homepages and obscure sites.

Yahoo!
For many years Yahoo! was a popular subject directory with a widely developed classification system. Later Yahoo! was enlarged with the facilities of a search engine. This was possible by buying indexes from other search engines. Yahoo! is a popular, large search engine that also can be used as a subject directory. But the emphasis lies now clearly on the search engine.

Ask Jeeves
Ask Jeeves was in the beginning years one of the rare search engines where you could ask your question in ordinary, natural language. Now the emphasis is less on Natural Language Processing but more on the search technology developed by Teoma. Ask Jeeves offers some popular applications such as: Map search, Movie search, White pages search, Dictionary search, Weather search, Product search, News search, Stock search.

Teoma
Owned by Asked Jeeves, determines results by ranking a site based on its subject-specific popularity (the number of Web pages about the subject that reference this page) as well as its general popularity (the number of all the WebPages that reference this page).

Hotbot
This is a so called "unified front-end" for the search catalogs of Hotbot, Google and Ask Jeeves. You can select the catalog you want to search, and after entering the search term, you can easily view the results from the other catalogs just by activating the respective buttons. Strictly speaking, Hotbot is neither a search engine, nor a meta searcher. This hybrid tool is characterized by its extensive Advanced Search options. In contrast to most other search engines, operators can also be used in combination with form options (image, video).

For a technical comparison of some general search engines, visit:

http://www.extremesearcher.com/chart1.html

This site compares the following major search engines: AllTheWeb, AltaVista, Google, HotBot, Lycos, Teoma, WiseNut, and Yahoo! Comparison parameters include: Size (pages), Simple Boolean Options, Full Boolean Operators, Phrase Searching, Proximity, Truncation, Title field, Date field, URL Field, “Links to “ a URL, Language, Media searching, Case Sensitivity, “Common” Keyword Search, Web Directory Attachment, Results Clustering, Output format Options, “Paid Site” Prioritization, “Similar Pages” Links Associations, Additional Outputs along with results, and “Notable” Special Features.