You may be more familiar with the broader term of evidence synthesis which encompasses all the different types of systematized reviews. A bit more inclusive of a term, evidence synthesis is more often used in the social sciences but really encompasses all systematized reviews from all disciplines. For more about the different types of reviews, the article A typology of reviews: an analysis of 14 review types and associated methodologies provides brief overviews of the different types and their methodology.
For many of your searches, you can employ a more systematic approach to how you search, where you search, and what items you include in your review. Systematized searches tend to be more comprehensive - both in the terms used and the databases used - and with the goal of being transparent about the choices made and providing a reproducible methodology. Even if you are not doing a full systematic review, you can borrow aspects of this methodology to give more structure to your review methodology and have a means for communicating how you found what you have.
So What are We Really Talking About?
While systematic reviews are becoming more common in social sciences, SR are much more common within the medical and health sciences arena. They are often done to address a very specific question or might be done to map the literature to determine where the gaps are within the published literature. For more on the steps of the process, check out the PRISMA checklist or UC San Diego Library's Preparation Checklist.
Ready to dive in on a systematized search? Want more details of how to do that? Check out our self-study guide: Search for Evidence in a Systematic Review - a comprehensive guide on the systematic search process
Check out this video for a good overview.