Encyclopedia of Computer Science and Technology

search engine 423AND, OR, or NOT. Thus, a search for “internet and statistics”will find only pages that have both words. Someengines also allow for phrases to be put in quote marks sothey will be searched for as a whole. A search for “internetstatistics” will match only pages that have these two wordsnext to each other.Because of the huge size of the Web, even seeminglyesoteric search words can yield thousands of “hits”(results). Therefore, most search engines rank the resultsby analyzing how relevant they are likely to be. This canbe done in a simple way by comparing the frequency withwhich the search terms appear on the various pages. Moresophisticated search engines such as Google can determinehow relevant a word or phrase seems to be becauseof its placement or presence in a heading or how often asite is referred to from other sites (see Google). Somesearch engines also offer the ability to “refine” searches byadding further words and performing a new match againstthe set of results.Limitations and Future of Search EnginesSearch engines do provide many useful “hits” for bothcasual and professional researchers, but the current technologydoes have a number of limitations. Even the mostcomprehensive search engines now reach and index only asmall fraction of the total available Web pages. One way tomaximize the number of pages searched is to use a “metasearch”program such as Copernic, which submits a user’ssearch to many different search engines. It then collates theresults, removing duplicates and attempting to rank themin relevance.Even with “relevancy” algorithms, searches for broad,general topics are likely to retrieve many less-than-usefulhits. Also, current search engines have difficulty findingimage and sound (music) files, which are among themost sought-after Web content. This is because the searchengine cannot recognize graphics or sound as such, onlyfile names or extensions or text descriptions. Searchengines also vary considerably in their ability to read andindex files in proprietary text formats such as MicrosoftWord or Adobe PDF.Once mainly an auxiliary tool for Web portals, searchengines have become a major business, and a variety ofnew types of search engines have proliferated. By combiningsearch with paid advertising and delivery of a varietyof services, Google in particular has become one of theWeb’s biggest success stories. In turn, Web-site owners haveattempted to use various techniques to “optimize” or raisethe ranking of their pages in search results, while Googlehas quietly tweaked its “page rank” algorithm to keep suchefforts in check.Two major search trends that can be seen in Googleare specialized searches and local search. Google offers avariety of search options to target images, video, news, evenblogs. Local search (such as Google Maps) combines mapswith lists of local businesses, making it easier for users tofind, for example, hotels near a given airport (see mappingand navigation systems). Services such as Google MapsStreet View even provide for a street-level closeup view ofCopernic, a “metasearch engine,” can pass a user’s request to manydifferent search engines and then prioritize and collate the results,weeding out duplicates. (Unfortunately some results are still muchless useful than others.)a neighborhood—almost a virtual tour, although this hasraised privacy concerns. Google offers an extensive programminginterface that is available to Web developers, aswell as an easier-to-use facility for creating custom mapdisplays (see mashups).In the future artificial intelligence techniques may makeit possible for search engines to recognize types of imagesor sounds through pattern recognition. Search engines maybe able to respond more appropriately to “natural language”queries such as “How many pages are there on the Web?”and find the answer, or at least Web pages that are likely tohave the answer. (Current services of this type such as Ask.com tend to give hit-and-miss results.)For now, search engines remain a useful tool, but systematicresearchers should complement their results with linksfrom portals and recommendations from authoritative sites.Further ReadingBatelle, John. The Search: How Google and Its Rivals Rewrote theRules of Business and Transformed Our Culture. New York:Penguin, 2005.Dornfest, Rael, Paul Bausch, and Tara Calishain. Google Hacks:Tips & Tools for Finding and Using the World’s Information. 3rded. Sebastapol, Calif.: O’Reilly, 2006.Kent, Peter. Search Engine Optimization for Dummies. Hoboken,N.J.: Wiley, 2006.Milstein, Sarah, J. D. Biersdorfer, and Matthew MacDonald. Google:The Missing Manual. 2nd ed. Sebastapol, Calif.: O’ReillyMedia, 2005.Moran, Mike, and Bill Hunt. Search Engine Marketing, Inc.: DrivingSearch Traffic to Your Company’s Web Site. Upper Saddle River,N.J.: IBM Press, 2005.Purvis, Michael, Jeffrey Sambells, and Cameron Turner. BeginningGoogle Maps Applications with PHP and Ajax: From Novice toProfessional. Berkeley, Calif.: Apress, 2006.