A systematic literature review (SLR) identifies, selects and critically appraises research in order to answer a clearly formulated question. The systematic review should follow a clearly defined protocol or plan where the criteria is clearly stated before the review is conducted.

It is a comprehensive, transparent search conducted over multiple databases and grey literature that can be replicated and reproduced by other researchers.

It uses explicit, systematic methods that are selected with a view to minimizing bias, thus providing more reliable findings from which conclusions can be drawn and decisions made. Systematic literature reviews originated in medicine and are linked to evidence based practice.