The Yahoo! Directory and Yahoo! Search work together to bring you the information and resources you are looking for.
Yahoo! Search returns a list of web pages containing the words you entered. These results are a combination of relevant web pages and web sites provided by Yahoo! Search and the Yahoo! Directory.
The Yahoo! Directory is a human-created and maintained library of web sites organised into categories and subcategories. Yahoo! editors review these sites for potential inclusion in the Directory, and to evaluate the best place to list them.
For example, you can see a full listing of general sites related to dogs by visiting Yahoo!'s Dogs category. (Click the "Directory" link above the search box, type "dogs" in the search box, and click "Search".) Sites about more specific dog-related subjects are listed under appropriate subcategories.

The Yahoo! Directory is helpful when:
You can browse this list of sites and subcategories, or search for "casting" services just within Talent Agencies, rather than on the entire Web. This guarantees your results won't refer to another kind of casting, such as plaster or die casting.
In this category, you'll find listings for individual creatures from antlions to wasps, along with such topics as entomophagy (insects as food) and pest management. Web Results for "bugs" alone give you a much narrower view.
The hand-built Yahoo! Directory paired with the technology of Yahoo! Search offers a useful, unified source of online information.