Literature reviews enable a researcher to learn about (and explain) the research already done on a topic or issue. It allows for one to learn what other researchers are doing in a particular field of study, which is used as evidence of a supporting argument in new research.
Literature reviews are also an excellent source for determining how other researchers have designed their projects, definitions of terms or problems, and hypotheses that have already been tested.
A wide variety of resources can be included in a literature review, such as: books, journal articles, news articles, working papers, conference proceedings, websites and reports. These resources provide overviews of a topic, history of approaches to a problem, descriptions of research methods, and the bibliographies used to create them.