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A literature review is a document or section of a document that collects key sources on a topic and discusses (summarizing and/or synthesizing) those sources. Literature reviews may trace the historical development of knowledge, describe current knowledge on the topic, critique past research, identifying gaps in knowledge/research, proposing new directions for research, and/or reconcile the evidence in order to inform policy and practice
While there are many types of literature reviews, they largely fit into two broad categories:
Narrative reviews, like other review approaches, summarize and/or synthesize prior work in a particular area and may discuss areas for future work. Narrative reviews typically do not include a methods, and identification and selection criteria for sources is usually implicit.
A systematic review is a review of the literature that is conducted in a methodical manner based on a prespecified protocol and with the aim of synthesizing the retrieved information. A systematic review methodology should be transparent, methodical, and reproducible.
A meta-analysis is a type of systematic review that statistically combines data of individual studies leading to more powerful analyses and potentially more sweeping conclusions.
Systematic review procedures are used most often used in medical research, though systematic review use in fields beyond the health sciences is growing. Below are procedures, standards, or other guiding documents for conducting systematic reviews for fields other than health sciences, or which are for health sciences but which have been used/adapted for other fields:
Evidence-Based Software Engineering and Systematic Reviews by 
Doing a Systematic Review: A Student's Guide by 