A literature review provides an overview of previous research on a topic that critically evaluates, classifies, and compares what has already been published on a particular topic. It allows the author to synthesize and place into context the research and scholarly literature relevant to the topic. Most scholarly books and articles begin with a review or at least a short characterization of the literature as a way of laying the groundwork for the authors' thesis. For researchers, this can be a great way of identifying key papers on the topic.
Hot tip: JSTOR, using the advanced search that ticks the "Sociology" subfield box is an excellent place to start a literature review. With the subfield checked, you can search by keyword or by a term in the abstract and be good to go in terms of finding literature.