A case-control study is a type of observational research used to identify factors that may contribute to a specific outcome, such as a disease. In this study design, researchers compare two groups: one group with the outcome of interest, known as the cases, and another group without the outcome, called the controls. By examining the differences in exposure to potential risk factors between these groups, researchers can infer associations. These studies are particularly useful for studying rare diseases or outcomes, as they allow researchers to gather data more efficiently than other study designs, like cohort studies. However, case-control studies cannot establish causation, only associations, due to their retrospective nature.