A search engine functions, in the following order
- Web crawling
- Indexing
- Searching
Web search engines work by storing data about numerous web pages, which they reclaim from the WWW itself. These pages are reclaimed by means a Web crawler, a robotic Web browser which follows each link it observes. Exclusions can be made by making use of robots.txt. The contents of every page are then analyzed to resolve how it must be indexed. Information about web pages is store in an index database for use in later query. A few search engines, like Google, store all or portion of the source page and data about the web pages, but others, such as AltaVista, store each word of all pages they find. This cached page always hold the real search text because it is the one that was actually indexed, so it can be especially useful when the content of the modern page has been updated and the seek out terms are no longer in it. This problem may be considered to be a placid form of linkrot, and Google's usage of it raises usability by gratifying user view that the search terms will be on the return webpage. This satisfy the principle of least amazement since the user in general expects the search terms to be on the returned WebPages. Increased search relevance make these cached pages very helpful, even ahead of the fact that they may contain information that may no longer be available in another place.
When a user enter a query into a search engine, by using key words, the search engine examines its index and provide a list of best-matching web pages according to its criterion, generally with a small summary containing the document's heading and at times parts of the text.
posted by sarah
@ 3:28 PM
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