Search engine is a computer program used to find information stored on computers or on the internet. Some search engines are important parts of database management systems. Such systems are programs that manage a body of information stored in a computer. The best-known search engines help people find websites. The internet’s websites contain information on practically every subject. Unlike the knowledge in an encyclopedia, however, this information is not neatly organized. When a user wants information on a particular topic, search engines help locate that material.
To find the appropriate information, search engines use indexes that summarize the contents of websites. The user begins by typing a query of one or more words, called keywords or search terms. These terms describe the user’s question or topic of interest. The search engine then returns a list of links (interactive connections). The links connect to websites related to the search terms.
For example, a user seeking information on the Great Chicago Fire of 1871 might begin by entering the word Chicago. But this search would return millions of matches, many of which the user would not want. If the user added the keywords fire and 1871, far fewer matches would result. Most would likely contain relevant information. Modern search engines are programmed to understand the context of many search terms. They may even suggest related queries or ways to narrow a search.
Most search engines use a spider, also called a web crawler, a program that follows hyperlinks, to visit web pages and retrieve their content. This content may then be placed in the search engine index. Companies that run online search engines typically make money by displaying advertisements alongside search results.
