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A Web Search Engine: General Information |
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| Date Added: March 20, 2010 06:28:34 PM | |
| Author: nactalia716 | |
| Category: Computers & Internet: World Wide Web: Software | |
Every day we use the Internet and search engines in particular when seeking information. The search results are normally provided in the form of a list and are normally called hits. The data may contain web pages, images, information and other types of files. Some search engines also accumulate data available in databanks or open directories. If compared with Internet directories that are maintained by human editors, search tools operate automatically or are a mix of algorithmic and human input. Internet search tools function by storing data about a huge number of web pages which they retrieve from the WWW. These pages are retrieved by a web crawler, or differently called a spider. It is an automated Web browser that follows every link it discovers. The content of each page is then analyzed to determine how to index it. Words, for example, are removed from titles, headings and subheadings or special fields called meta tags. Data about web pages are stored in an index databank for further use in queries. Some search tools, such as Google, save and store the whole or part of the source page (referred to as a cache) as well as data about web pages, whereas others, such as AltaVista, save and store every word of every page they discover. This cached page always comprises the actual search text, because it is the one that was actually indexed. Consequently, it can be very useful when the content of the current page has been updated and the search words are no longer in it. When a web user types search words in the search field, the software program browse through its database and shows a listing of best-matching web pages according to its parameters, usually with a brief summary coupled with the title of the document and at times extracts from the text. Some search engines provide an advanced feature called proximity search that allows users to define the distance between key words. The usefulness of a search engine depends on the relevance of the result set it provides. Since there may be millions of web pages that include a certain key term or word combination, web pages can be grouped into relevant and irrelevant ones. The majority of search tools employ methods to rank the results to list the "best" results first. The way a search software programme shows web pages is search engine-specific. The methods also alter with time, since the use of Internet services undergoes alterations and advanced techniques are developed. |
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