Literature reviews are either standalone publications or part of a paper as background for an original research project. A literature review, as a section of a more extensive research article, summarizes the current state of the research to justify the primary research described in the paper.
For example, a researcher may have reviewed the literature on a new supplement's health benefits and concluded that more research needs to be conducted on those with a particular condition. This research gap warrants a study examining how this understudied population reacted to the supplement. Researchers need to establish this research gap through a literature review to persuade journal editors and reviewers of the value of their research.