Purpose of the Literature Review
Provide a context for the research
Justify the research
Ensure the research hasn't been done before (or that it is not just a replication study)
Show where the research fits into the existing body of knowledge
Enable the researcher to learn from previous theory on the subject
Illustrate how the subject has been studied previously
Highlight flaws in previous research
outline gaps in previous research
Show that the work is adding to the understanding and knowledge of the field
Help refine, refocus or even change the topic