Types of Web search Tools
Types of Web search Tools
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Meta-Search Engines |
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Meta-search engines are "databases of databases," and should be used when you value speed and quantity of results over accuracy. They provide a single interface where you can enter a search, and your search is then simultaneously sent out to a number of different search engines. The results from the many search engines are then gathered and combined for you by relevance or search engine. Meta-search engines provide a quick way to find many results. However, you sometimes cannot refine searches with a meta-search engine, and your search results may be less accurate than if you searched each individual search engine one at a time. Think of meta-search engines as the broadest way to start your search.
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Search Engines |
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A search engine is a searchable database of websites. Search engines work by taking a "snapshot" of the web. They have special programs called "spiders" or "robots" that go out on the Internet looking for new information, which they bring back to be indexed in the database. Search engines differ in how much of the Internet they look at, how often they index what they find, and how they organize and present their findings. Most search engines use mathematical formulas to rank or weight your results, based on factors like how often the words you searched for appear in the retrieved documents, or whether they are in the title or in the text, etc. No search engine covers every website that is out there. Because of this, you sometimes need to try your search in several search engines, or use a meta-search engine.
Subject
Directories/Guides
Subject guides are large collections of websites organized into subject categories to make it easier to browse for the type of information you want. They are well organized and provide you with information that has already been judged as particularly useful by someone who is usually well qualified to make decisions about those sorts of things. However, because they are put together by a human being (who can only stare at a computer screen for so many hours) and not a computer program that goes out and "fetches" information automatically, they provide a much, much smaller "picture" of the Internet than a search engine.
For More Information
There are several websites that provide links to many different search engines, and describe how they work and the differences between them. These two are good places to start.