A literature review is a piece of writing intended to critically evaluate material that has been published on a certain topic or research problem.
According to the APA Publication Manual, Sixth Edition, literature reviews can
A literature review can be published as a free-standing piece of writing or as a section of a larger work. For example, literature reviews are often published as a book chapter or within the introduction of a scholarly research article. Literature reviews should follow the general guidelines of an appropriate style and formatting guide, such as APA, MLA, or Chicago.