Q. What is an index?

An index can be a couple of different things in the world of libraries and information.

Concerning books, an index is an alphabetical list of keywords and subjects usually located in the back of a book or the last volume of a multivolume set of books that provides page numbers indicating where those keywords and subjects are discussed inside the book or set.

Concerning articles, an index is a list of articles appearing in certain publications during a certain time period, organized alphabetically by subject and authors' last names. Electronic library databases are also known as online periodical indexes and provide easy keyword access to articles.