Search directories are a common tool that people use when doing research on the Internet. However, search directories are not quite as common as search engines (for instance www.google.com). Instead, search directories are sorted by subject, so they tend to be more relevant. Also, when you search for something, you tend to come up with less hits. However, search directories do come with their disadvantages. Search directories are edited by people, so you might not be able to find resources for exactly what you're looking for. Also, it is common to come across dead links on search directories.

Here are some common search directories:
Yahoo http://www.dir.yahoo.com
Open Directory http://dmoz.org
LookSmart http://www.looksmart.com

There are also some common search directories for children:
Ask Jeeves for Kids http://www.ajkids.com
Yahooligans http://www.yahooligans.com

Search Directories are good because they have more relevant information, however they also have more disadvantages. They are not updated as often as a search engine. Also, due to the fact that they are edited by people, they tend to be more biased.