A systematic review starts from a clearly defined, researchable question.
A plan (protocol) is developed to ensure all available evidence on the topic can be located, along with clear criteria identifying what will and will not be included. This protocol is often registered with a systematic review library, facilitating peer review, and avoiding the need for others to spend time on the search.
The search is then refined and conducted, before articles are screened for relevance, then assessed for quality and appropriateness. Once the list of included articles is finalised, key data are extracted and analysed to produce a new perspective to the question based on the aggregated evidence.
The synthesis is then written up and submitted for publication.