| Every day we use Internet services and search engines in particular when searching for information. The search results are commonly called hits and are provided in the form of a list. The information may comprise web pages, images, data and other types of files. Some search engines also gather data available in databases or open directories. In comparison with Internet directories which are maintained by human editors, search engines operate automatically 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 finds. The content of each page is then analyzed to decide how to index it. Words, for example, are removed from titles, headings or special fields called meta tags. Data about web pages are stored in an index catalogue for further use in queries. Some search tools, such as Google, save and store the entire or part of the source page (differently called a cache) as well as information about web pages, while others, such as AltaVista, store every word of every page they find. The cached page always contains the initial search text, since it is the one that was actually indexed. So, it can be very useful since it holds information that may no longer be found anywhere else on the Internet.When an Internet user types search words in the search field, the software programme looks through its database and displays a list of best-matching web pages in accordance with its criteria, usually with a short summary coupled with the document's title and sometimes parts of the text. Some search tools have introduced an advanced feature called proximity search which allows users to determine the distance between search terms.The relevance of the result set determines the usefulness of a search engine. Since there may be millions of web pages that include a particular word or phrase, some pages may appear to be more relevant and popular than others. The results can be ranked to show the "best" ones first.How a search engine decides which pages are the best matches, and in what arrangement the results should be displayed, varies from one engine to another. The methods also alter in time, as the use of the Internet undergoes alterations and advanced techniques are developed. |
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