Discover How Search Engines Work

Net search engines work by storing information about a giant number of Internet pages, which they retrieve from the WWW itself. Info about net pages is stored in an index database to be used in later questions.

Some search engines,eg Google, store part of the source page ( known as a cache ) as well as info about the net pages, while some store each word of each page it uncovers,eg AltaVista. This cached page always holds the search text since it's the one that was really indexed, so it can be really helpful when the content of this page has been updated and the search terms are now not in it. This problem could be said to be a mild form of linkrot, and Google's handling of it increases usability by gratifying user expectations the search terms will be on the returned net page.

This satisfies the concept of least mystification since the user typically expects the search terms to be on the returned pages. Increased search significance makes these cached pages extraordinarily helpful, even beyond the incontrovertible fact that they may contain info that may not be available elsewhere. When a user comes to the search engine and makes a question, sometimes by giving keywords, the engine looks up the index and gives a listing of best-matching net pages according to its standards, often with a short outline containing the document's title and occasionally parts of the text. An sophisticated feature is vicinity search, which permits you to outline the space between keywords. The utility of a search engine depends on the importance of the results it gives back.

Whilst there might be millions of Net pages that include a selected word, some pages could be more important, well-liked, or authoritative than others. How a search engine decides which pages are the best matches, and what order the results should be shown in, varies widely from one engine to another. The methods also change over time as Net use changes and new systems develop. Most Internet search engines are commercial ventures supported by advertising cash and, as a consequence, some employ the debatable practice of permitting advertisers to pay money to have their listings ranked higher in search results. The overwhelming majority of search engines are run by personal firms using exclusive algorithms and closed databases, the hottest now being Google, MSN Search, and Yahoo! Search.