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SEO Softwares ->Learn SEO Basics -> Web Search Engines A Web search engine is a software tool that can be downloaded or uploaded; though preferred featured programs are usually provided anyway with most modern computers, which is designed to search for information in response to search requests on the World Wide Web. Search results, often called ‘hits’ are usually presented in two lists, the list on the left of the page ranking the results by organic (unpaid) match to content and the list on the right showing sponsored (paid) results. The information returned from a search request can consist of web pages, images, information and other types of files. Search engines may also mine data available in newsbooks, databases, or open directories. Unlike Web directories that human editors maintain, search engines perform algorithm operations or a combination of human and algorithmic input to generate their results. How Search Engines Works
Search engines operate by accumulating and storing information retrieved from the World Wide Web about countless web pages it has ‘crawled’. A Web crawler or ‘spider’ is a ‘behind the scenes’ automated program within search engines for gathering web site listings through the use of automatic web crawling. The search engine's crawler, ‘spider’ or ‘robot’ can “read” web page coding and page text contents, and can follow links to other hyperlinked pages. It duplicates and stores any web pages found for the search engine's database or index where it can be used for later queries, though initiating robots.txt can direct exclusions from the crawl. The retrieved page content then undergoes analysis to determine its indexing based on title word extraction, headings, and/or special fields known as meta tags. Search engines like Google, store all or sometimes only part of the source page in a cache and web page information. Others like AltaVista, store every single word of every single page found. The cached page will always hold the actual search text used since it is the one that was actually indexed, proving a valuable archive resource when content of a current updated page no longer has the search terms on it. This might be regarded as a mild case of linkrot that old information is taking up space in the database but Google's handling of it does increase usability through satisfaction of user expectations that any search terms will show up the returned webpage. Here then, the principle of least astonishment is satisfied, as users normally expect their search terms to appear on returned pages. The increased search relevance is what makes such cached pages valuable and productive, despite the fact they might contain data no longer available elsewhere. After entering a query into a search engine through key words, the engine’s examination of its index will provide a listing of ‘best-match’ web pages according to its particular criteria, normally containing a short summary with the document title and a short excerpt of its text. Most of the search engines support the use of the boolean operators AND, OR and NOT for further refinement of a search query and some search engines also provide proximity search, an advanced feature that allows a user to define the distance between the keywords used in a search. A search engine’s value is dependent on the actual relevance of a returned result set. It is possible that millions of various web pages could contain certain words or phrases that make up the search query, and of them some may have more relevance, popularity, or authority than others so search engines employ ranking techniques to the results in order to provide the list of "best" results first. There is wide variation between search engines as to how they reach their decision for which pages they deem to be best matches, and the order in which the results should be shown. The methods are ever changing as new techniques evolve and Internet usage changes. Web search engines, generally, are commercial by nature and most are supported by revenue from advertising with the result that some of them allow advertisers to pay money to have their listings ranked higher up in search results. Paid Sponsors or Paid Listings are also terms used as titles or column heads on search engine results pages (SERPs) to identify paid advertisers and distinguish between organic and paid listings. Through the separation of paid listings and organic results, searchers can come to their own independent decisions about site trust and make uninfluenced purchases. [The labeling came about as a result of an FTC complaint filed by Commercial Alert in 2001 that alleged the confusion that was caused amongst consumers from seeing both mixed paid and unpaid results together without identification, constituted advertising fraud.] Search engines that do not accept payment for their results create revenue by running search related ads alongside their organic or natural search engine results and they gain money each time a click is made on one of them. Revenue projections for the web search portals industry suggest growth by13.4% in 2008, with an expected increase for broadband connections of 15.1%. Industry revenue projections forecast a rise by 56% between 2008-2012 as Internet penetration has yet to reach complete saturation in US households. Broadband services too have forecast projections they’ll continue to account for an increasing share in the domestic Internet users sector, rising by 2012 (it’s predicted) to 118.7 million, with the share growth increase accounted for by continued uptake of technological advance through high speed cable and fiber-optic lines. |
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