A literature review, also known as a lit review, is an in-depth analysis of existing research on a particular topic. It is used to identify trends, debates, and gaps in the research so that new studies can be designed to address them. A critical literature review is a type of lit review that evaluates the quality of the research and its relevance to the topic. It involves assessing the strengths and weaknesses of the research and determining whether it is suitable for the purpose of the study.