To help define the focus of your research topic.
To identify research already conducted in your field of interest, find gaps in existing scholarship, and avoid repetition of previous research.
To become familiar with significant earlier research and with current progress and/or controversy in your field of interest.
To diagnose the strengths and weaknesses in the works pertaining to your field of interest.
To assess the experts, theoretical approaches, methodologies, results, conclusions, and possible opportunities for future research in your field of interest.