Clinical trials are a core part of the medical research process. They allow scientists to test whether new treatments, drugs and practices will work before they try them out on patients in real life settings. Clinical trials often have strict guidelines for participation because participants must be healthy adults who meet certain criteria or suffer from specific conditions; additionally, clinical trial subjects may agree to participate in studies that are paid compensation but do not provide any other form of payment outside of their involvement with the study itself (such as through insurance).