RCT, or randomized controlled trial, is a type of scientific study design used in medical and social research. In an RCT, participants are randomly assigned to either an experimental group, which receives the treatment being studied, or a control group, which does not receive the treatment or receives a different treatment for comparison. This randomization helps to ensure that any differences observed between the two groups are due to the treatment being studied, rather than other factors. RCTs are considered one of the most reliable methods for evaluating the effectiveness of medical interventions.