Where is the subject catalog of the web?There are several. There is no mechanism inherent in the web which forces the creation of a single catalog (although there is work underway on automatic mechanisms to catalog websites). Also be sure to check out the entry on how to search the web.
Yahoo (URL is <URL:http://www.yahoo.com/> ) is probably the most complete hierarchical, topical index of websites, and also features a sophisticated search facility.
The original catalog of the web was the WWW Virtual Library (URL is http://www.w3.org/hypertext/DataSources/bySubject/Overview.html ), maintained by CERN and later by the W3 Consortium. The Virtual Library is a good place to find resources on a particular subject, and has separate maintainers for many subject areas.
World Wide Web FAQ