Concise and descriptive, it should illustrate the research problem and the methodology involved.
Readers look to abstracts to decide if a paper will be useful to them. Abstracts are a short, (usually 200-500 word) summary of the paper, providing the research question, methodology, and a generalized description of results and findings. Since an abstract summarizes the paper, they are generally written last, after the paper is finished.
What is going on in this paper? What is the issue/problem being investigated? Why is this topic worth researching? Explain what you hope to discover with your research.
What current scholarship exists on your problem? Conduct searches of library databases to discover what is currently known about your topic. Discuss the current status of scholarship, and the methodologies used. The literature review should contain peer-reviewed articles and scholarly books.
How are you conducting your research? Explain the tools you use to collect data, such as surveys, focus groups, samples, etc. You should provide your readers with enough detail so that they can replicate your study.
What did you discover? This is where you will display what your research found. Use graphs, charts, interview responses. This section is just a recitation of facts and findings
Expand on your results. Why is what you found out interesting. What does it mean? How does your research impact your topic? How does it solve the problem? What are the implications of your study? What will be the next steps to take with research, based on your findings?
Every research paper contains a bibliography of all the outside sources used in the paper.
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Adapted from "Components of a Research Paper," Center for Innovation in Research and Teaching, Grand Canyon University, https://cirt.gcu.edu/research/developmentresources/tutorials/researchpaper
The Writing Center at UNC Chapel Hill has a great handout on how to write a literature review.
These are examples of literature reviews. Most of them follow a thematic approach, where they discuss how the literature deals with aspects of their topic.