A literature review is a summary of studies related to a particular area of research. It identifies and summarizes all the relevant research conducted on a particular topic. It is important that your literature review is focused. Therefore, you should choose a limited number of studies that are central to your topic rather than trying to collect a wide range of studies that might not be closely connected.

Literature reviews help you accomplish the following:

• Evaluate past research 
  Collecting relevant resources will help you see what research has already been done. This will also help avoid duplication.

• Identify experts
  It is important to identify credible researchers who have knowledge in a given field, in order to seek their help if you get stuck with certain aspects of your research.

• Identify key questions 
  Your ultimate aim is to bring something new to the conversation. Collecting resources will help you determine the important questions that need to be addressed.

• Determine methodologies used in past studies
  Knowing how others have approached a particular topic will give you the opportunity to identify problems and find new ways to research and study a topic. If the reported methodology was successful, you can use it and save time that you would otherwise be spending on optimization.