Another option when searching for web sites about a certain topic is to use a web directory. In a web directory an indexer selects web sites and then assigns them to categories. These categories are often organized hierarchically, starting with several broad categories which are divided into subcategories. Each subcategory is then divded into another level of subcategories or websites and the process continues until there is no further need to subdivide a category. The following example is taken from Yahoo's web directory.
Subcategories (Level 1): Higher Education, K-12
Subcategories (Level 2): Colleges and Universities, Distance Learning
Subcategories (Level 3): United Kingdom, United States
Subcategories (Level 4): Private, Public
Subcategories (Level 5): Massachusetts, Michigan
Subcategories / Web Sites (Level 6): University of Michigan
The last level will contain only links to web sites. Intermediate levels may contain both subcategories and links to web sites that are appropriate for that level.
Web directories may be included on a search engine's web site or as independent web sites. Here are examples of just a few web directories: