what is a literature review in a dissertation

A literature review is built on the work of others, but you shouldn’t rely on the words of others when expressing their views. For this reason, Paraphrasing is a particularly important skill when writing a literature review.
What is a literature review? What’s the point of it? How do you evaluate literature? Use our Writing the literature review guide for answers to these questions and more.

(from University of Minnesota’s Dissertation Calculator)
Step 2: Identify gaps in your research based on step 1 review.

References:

http://guides.ucf.edu/c.php?g=78838&p=518756
http://library.soton.ac.uk/sash/dissertation-planner/writing-literature-review