The most common browsers are Microsoft Internet Explorer, Netscape Navigator, and AOL's versions of each. While a search engine indexes the internet with automatic computer programs, a directory is a list of sites laboriously compiled by hand.
Directories are thus much easier to use than search engines, but they can produce limited results.
A system for hierarchically organizing and navigating documents on distant computers, implemented extensively at college campuses and research facilities in the early 1990s. It was quickly overshadowed by the much more usable world wide web interface and is rarely used today. Meta-directories can be among the best starting points for research on the internet, because they usually classify other directories by subject, which will in turn list specific pages. See also smtp. Similarly, to send email or read the usenet all of the computers involved have to use one agreed-upon set of instructions, or one protocol, for that function.