It is a reference to a text or part of a text identifying the document in which it may be found.

It is a bibliographic tool in print or electronic format that lists all referenced or cited source items published in a given time span.

An arrangement whereby software or artistic work may be used, modified, and distributed freely on condition that anything derived from it is bound by the same conditions.

It is one of the several public copyright licenses that enable the free distribution of an otherwise copyrighted work. A CC license is used when an author wants to give people the right to share, use and build upon a work that they have created.