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Get a Better Look At Web Search Engines

Date Added: March 20, 2010 10:48:00 PM
Category: Directories
A web search engine is a tool designed to search for data on the Web. The search results are commonly provided in the form of a list and are normally called hits. The information may contain web pages, images, information and other types of files. Some search tools also accumulate information available in databases or open directories. In comparison with Internet directories which are maintained by human editors, search engines operate algorithmically or are a mix of human and algorithmic input. Internet search engines operate by storing information about numerous web pages which they retrieve from the INTERNET. 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 decide how to index it. Words, for example, are extracted from titles, headings and subheadings or special fields called meta tags. Data about web pages are saved and stored in an index database for further use in queries. Some search tools, such as Google, store the entire or part of the source page (also called a cache) and data about web pages, while others, such as AltaVista, save and store every word of every page they have found. This cached page always comprises the initial search text, because it is the one that was actually indexed. So, it can be very useful when the content of the current page has been changed and the search words are no longer in it. When a web user types search words in the search field, the engine browse through its catalogue and shows a list of best-matching web pages according to its criteria, normally with a brief summary containing the title of the document and sometimes extracts from the text. Some search tools have introduced an advanced option called proximity search which allows users to determine the length between key words. The relevance of the results determines the usefulness of a search engine. Since there may be millions of web pages containing a certain word or phrase, web pages can be grouped into relevant and irrelevant ones. Most search engines use techniques to grade the results to feature the "best" results first. How a search engine determines which pages are the best matches, and in what arrangement the results should be displayed, varies from one engine to another. The techniques also alter in time, because the use of the Internet undergoes alterations and new techniques are developed.
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