When you use one, you are actually searching the result of this inventory of web sites found during the crawl.
All search engines have their strengths and weaknesses.
They differ in the size and nature of their coverage, in the way they rank results, and in the information that is displayed about each result. Subject Guides or Directories Subject guides or directories do some of the work for you, by organizing their findings in categories that might be useful for your purposes. Examples include Yahoo and the Argus Clearinghouse . Meta-Search Engines Metasearch engines allow you to search using several search engines at once, so that you can utilize the different strengths of many engines without having to enter your search more than once. Others include MetaCrawler and Dogpile.