Academic libraries serve a very different function from the other types of libraries. These collections exist to support the teaching and research needs of the scholars, students, and researchers of the institution with which they are affiliated. Large academic libraries collect scholarly materials published in many languages and from all over the world. Even small academic libraries reflect the teaching mission of the institution. Specialized, technical, detailed materials are the norm in most academic collections of any size.
Unlike use of public libraries, use of academic library collections may be restricted to some extent. You may have to apply for a special privilege card or pay a fee in order to gain access to the online catalog and check out materials, or you may only be able to use materials if you go in person to the library. In extreme instances, unauthorized users may not even be able to enter the building.
However, if the topic you are researching is of a national or an international nature, if it involves specialized or technical subject areas, or if it is likely to cover controversial ideas, then an academic library collection is probably one of the best places to look. In addition, if you have been a student at a university and are an alumni society member, it is likely that you have free access to that library system and to a network of materials from other academic libraries as well.