A subject directory has links compiled by professional librarians, experts in their subjects and teachers, where information is categorized by into specific subjects.
The advantage of using a subject directory like the Internet Public Library(IPL) is that the information that a teacher or student can search is going to be useful for various reasons. It was compiled by professionals and experts that allocate the information in categories. It is easy to use. It contains extensive directories of reference materials such as books, magazines, or newspapers. The information is well organized and is easy to navigate. The IPL was created by the members of the School of Information and Library Studies at the University of Michigan.