The first, most basic tools for finding resources on the web are directories. Directories create categories under which web sites can register themselves according to their main focus, making the web page owners themselves responsible for maintaining the listing. Some directories are topic specific while others are more generalized. Among the first directories ever formed, and quite possibly the largest, is Yahoo! Yahoo is a generalized directory and has approximately a dozen primary categories including Arts, Education, Health, News, and Science. Each major category is then broken out further into smaller related categories. For instance, under Science, you will find Biology, Astronomy, Engineering, etc. If you are looking for the site of a specific company or organization, a directory may be a good place to look. Also, if you have a general topic in mind and are looking to narrow it or if you just want to see what interesting sites dealing with that topic might exist, a directory may be an ideal place to start. Most directories have a search engine feature that allows you to search the directory in case you are sure which heading a subject may be under. Some directories list only reviewed sites. In other words, they look at each site to be sure that it is useful before listing it in their directory.

Go to the Yahoo! Home Page, and from there choose the Science subject listing. Look at the various sub-categories. If you are taking this lesson as part of a group, give your impression of the usefulness of this method of "cataloging" sites.