Software robots survey the Web and automatically create listings for search engines.
Most search engines have a subject directory component that allows you to browse by topic in addition to typing in search terms. Choose from this group of popular search engines and search engine collections. Metasearch Engines Metasearch engines, also called metacrawlers, search several search engines at once. Subject Directories Directories depend on human selection for their listings and organize their resources into broad subject categories. Some subject directories also allow you to type in terms to look for matches in the sites selected by the directory.