A citation is a reference to an item that gives enough information in order for you to identify it and to be able to find it again.
Generally, citations include four elements:
The source information is the clue to figuring out what kind of resource the citation points to:
Other types of publications (audio/visual materials, government documents, dissertations, etc.) will generally include the basic four elements, but will also include enough information in order for the person reading the citation to identify both the type of information source, as well as how to find the information again.
"Broadly, a citation is a reference to a published or unpublished source (not always the original source).
A prime purpose of a citation is intellectual honesty: to attribute prior or unoriginal work and ideas to the correct sources, and to allow the reader to determine independently whether the referenced material supports the author's argument in the claimed way."
Citations can be found in the bibliography or works cited section of books and scholarly articles as well as listed in the library's electronic or printed indexes and databases.