Directory sites place each web site in their database in one or more predefined subject categories following review by a human being.
A web site is included in a directory site’s database only after some human reviewer has judged it to be useful, informative, or otherwise worthwhile. Typical reasons a site might not be included in the database are because it isn’t unique enough, it isn’t guaranteed to remain around for long, or it doesn’t meet some other guideline or criteria.
A well laid out directory site defines the set of categories so that there seems to be only one natural choice at each level for the topic you are searching for. There is increasing consensus about the set of top-level categories, and most sites include at least the following twelve:
A good search method for directory sites is called “drilling down”, where you click as fast as possible on the next subcategory at each level until you get to the one you’re interested in. A well designed directory site will make this drilling down natural, since the structure will make it obvious which category to choose next at each level. You can take an indirect method and search the site using the techniques in the search section.
Resources. Some of the major Internet directory sites are listed below:
Directory sites were originally called WWW Virtual Libraries, so you can also find them by searching for “WWW Virtual Library“
Yanoff’s Internet Services list provides an interesting historical directory site listing.