A search engine is an automated tool which attempts to create a detailed and retrievable listing of Web pages. All search engines work more or less in the same way. The problem is that if you are looking for a general topic, search engines can turn back thousands of leads. No matter how carefully you craft your query, you'll probably have to sift through unrelated sites. It also takes time to check out every lead, even with those search engines that can create a bookmark file of the results.
Search engines use different methodologies for performing searches.
Search engines turn up leads based on objective criteria such as how many times a particular keyword is repeated within the text of a page, in a url, or page title. Some may search through all the text at an entire site while others simply scan the top page. As search engines have become the most frequently visited destinations on the Web, these for- profit ventures have taken advantage of the lucrative revenue potential. Many search engines cut deals with advertisers and content providers which may compromise the objectivity of their search listings. In other words, a content provider could pay a fee to a search engine to ensure that their page listings appears on the top of list.