The literature review is an integral part of any research project and is undertaken as a means of surveying what research has been conducted previously on a particular topic. There are many reasons for conducting a literature review, but one of the primary reasons is to establish a base line of what is already known on a topic before exploring the topic any further. The review typically involves a search of any previously published or presented materials that might have relevance to a prospective new study.
Alderman, Jim, "Conducting a Literature Review" (2014). Beginning Library & Information Systems Strategies. Paper 16.