The lines between directories, search engines and the deep Web are blurring. The deep Web is often represented by searchable news, phone books, dictionaries, maps, stock quotes, items in retail stores, multimedia files, etc. Directories are also present at some search engine sites, and sometimes their contents are searched along with content from the general Web. Directory results are sometimes placed before search engine results in order to steer users to the directory's content. This can be a useful way of getting at substantive content relating to your query.
Most subject directories are searchable.
For more information, see General Search Strategies later in this tutorial. These services illustrate vastly different policies for the selection and evaluation of sites to include in their collections. To see a selected list of these types of sites, follow this link. The Clearinghouse is one of several academic directories that selects and annotates sites for academic or searious researchers. To see a selected list of these types of sites, follow this link.