The very first step in any research design is to clearly state the research question. What is being explained? Just stating or knowing the research question will not be enough unless the finding is novel. Therefore, the researcher needs to say: What is new?
To know whether the finding is novel and what new things are being explored, one needs to know what the current wisdom is about the topic or related topics. Therein lies the importance of a literature review.
A literature review is exactly that — a review of the literature — a review of studies/research in journal articles and/or other publications that have already been conducted on your topic or subtopic. The Literature Review section should not merely describe and summarize the current information on the topic but also evaluate and compare the studies/research. More often than not, there will be apparent contradictions in the findings of different existing studies. It is the researcher’s job to shed light on the key differences and what underlying assumptions, or methodologies, or datasets lead to such differences. This will be helpful for placing the contribution of the current research work in the right context.
The literature review section plays a very important role in any research in the sense that familiarity with previous research will help in formulating your own research study. Once this literature review is developed, you will be in a better position to decide how to design a research method and collect and analyze the data. The literature review will further help you contrast and compare your results and conclusions with earlier research on the same question.