A literature review is a critical assessment of the literature pertaining to a particular topic or subject. It is a 'systematic, explicit, and reproducible method for identifying, evaluating and synthesising the existing body of completed and recorded work produced by researchers, scholars, and practitioners' Fink, (2005).
What's its purpose?
justify your research
provide context for your research
identify new ways, to interpret and highlight gaps in previous research
ensure that the research has not been done before
signpost a way forward for further research
show where the research fits into the existing literature