A Web Search Tools: How It Operates

An Internet search engine is a tool specially-designed to search for data on the Internet. The search results are commonly provided in the form of a list and are usually called hits. The data may consist of web pages, images, data and other types of files. Some search tools also gather information available in databases or open directories. In comparison to Web directories which are maintained by human editors, search engines function automatically or are a mixture of human and algorithmic input.
Internet search engines function by storing information about a huge number of web pages which they retrieve from the WWW. These pages are retrieved by a web crawler, also known as a spider. It is an automatically-controlled Web browser which follows every link it discovers. After that the content of each page is analyzed to determine 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 databank for further use in queries. Some search tools, such as Google, store the entire or part of the source page (also called a cache) as well as data about web pages, whereas others, such as AltaVista, store every word of every page they have discovered. The cached page always comprises the initial search text, because it is the one that was actually indexed. So, it can be very helpful when the content of the current page has been changed and the search words are no longer in it.
Once an Internet user has typed search terms in the search field, the engine carries out checks on its index and shows a listing of the most suitable web pages in accordance with its criteria, normally with a brief summary coupled with the title of the document and at times extracts from the text. Some search tools have introduced an advanced tool called proximity search which allows users to define the distance between key words.
The usefulness of a search engine depends on the relevance of the result set it gives back. Since there can 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 use techniques to grade the results to display the "best" results first.
How a search engine determines which pages are the best matches, and in what arrangement the results should be shown, varies from one engine to another. The techniques also change in time, because the use of Internet services alters and advanced techniques appear.

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A File Search Engine is a software programme which searches for websites based upon search terms. Here one can download mandingo.

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