Libraries Law Libraries Medical Libraries National Libraries Pres. Like any other resource, search engines work best when you know how to use them. Unfortunately, no two are exactly alike and some are better than others, depending on what you're searching for. More commonly referred to as crawlers or spiders, computer-generated indexes like WebCrawler scan the web looking for words relevant to your search. Directories like Yahoo are lists of sites edited by humans and organized by topic.
Many sites are a combination of the two.
Northern Light, for example, is a spider that uses folders you can search by subject, source description and type of document. The third category includes meta search engines, which search other engines for you. Google, MetaCrawler and Dogpile are all meta engines. Ask Jeeves is a meta engine that allows users to enter queries in the form of a question. Ask Jeeves For Kids gives 7-14 year olds access to a screened metasearch.