A systematic review is a research method where you start with a precise and delimited research area. The research area is systematically searched for relevant studies which are then quality assessed. Every research step in this method should be well described to ensure that the systematic review is transparent and reproducible.
Sometimes all of the steps above will not be followed. Journals, depending on discipline, can have other demands. Journals can also have different claims of how a systematic review should be conducted, so always check which guidelines you should follow.
Systematic reviews sometimes contain a meta-analysis, wherein the collected data is combined using statistical method.
Cochrane is an independent, diverse, global organization that collaborates to produce trusted synthesized evidence.
There are international guidelines for how a systematic review should be conducted and reported. Preferred Reported Items for Systematic Reviews and Meta-Analyses (PRISMA), is foremost intended for studies with a quantitative method but can also be used for qualitative studies.
Prospero is a database for systematic reviews, where you can search for ongoing systematic reviews and also register protocols when you start a project. Prospero only register systematic reviews.
Open Science Framework is a archive for preprints, datasets and study protocols. You can search for registered protocols and register your own project. OSF register protocols for different types of litterature reviews.
Figshare is a archive for preprints, datasets and study protocols. You can search for registered protocols and register your own project. Figshare register protocols for different types of litterature reviews.
There are several organizations that conduct systematic reviews from a specific methodology, for example Cochrane, Campbell Collaboration or Joanna Briggs Institute. Their methodology can be a support even if you're not doing the specific kind of review. The journal you are looking to publish in can also have methodology guidelines.