Systematic reviews gather ALL the relevant studies that have already been conducted on a specific clinical question.
They evaluate the studies, select the best ones, and synthesize their findings.
If they have found enough good quality studies, systematic reviews give clinical recommendations.
They're called "systematic" because they use pre-defined, rigorous, methodical, and clearly documented methods in each step of the research process. This reduces bias and ensures that the research is transparent so that readers can assess their quality.