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A Web Search Engine: A Detailed Analysis |
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| Fecha agregada: July 01, 2010 09:52:00 AM | |
| Autor: nactalia716 | |
| Categoria: Informática e Internet: Software | |
An Internet search engine is a software programme designed to search for data on the World Wide Web. The search results are usually presented in the form of a list and are normally called hits. The data may consist of web pages, images, information and other types of files. Some search tools also accumulate data available in databanks or open directories. Unlike Internet directories that are maintained by human editors, search engines work automatically or are a mix of algorithmic and human input. Web search engines work by storing information about a huge number of web pages which they retrieve from the INTERNET. These pages are retrieved by a web crawler, or differently called a spider. It is an automatically-controlled Web browser that follows every link it discovers. Afterwards the content of each page is analyzed to determine how it should be indexed. Words, for instance, are extracted from titles, headings or special fields called meta tags. Data about web pages are stored in an index database 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) and data about web pages, while others, such as AltaVista, save and store every word of every page they discover. This cached page always comprises the actual search text, since it is the one that was actually indexed. Hence, it can be very helpful because it comprises information that may no longer be found anywhere else on the Web. Once a user has typed search terms in the search field, the engine browse through its index and shows a listing of the most suitable web pages according to its parameters, commonly with a brief summary combined with the document's title and at times parts of the text. Some search tools provide an advanced feature called proximity search that allows users to determine the length between search words. The relevancy of the result set determines the usefulness of a search engine. Since there can be millions of web pages that comprise a certain key word or phrase, some pages may be more relevant and popular than others. The results can be ranked to show the "best" ones first. The way a search tool shows web pages differs from one engine to another. The techniques also alter with time, because the use of Internet services changes and advanced techniques are developed. |
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