Clinical trials are research studies that test new medical treatments on people who volunteer. These studies help doctors learn if new medicines, can improve people's health. Scientists need these trials to make sure new treatments are safe, work well, and don't cause too many side effects before doctors can use them with patients.

Before any new treatment can be tested on people, the FDA makes sure lots of testing and information is collected first. During a clinical trial, a doctor and a study helper will watch over you carefully, and you'll often get more attention than at regular doctor visits. Before you join a study, doctors will check if you're a good fit. They'll also tell you about any possible risks, benefits, and what to expect if you participate.

You generally don't have to pay for the medicines or treatments in clinical trials. Instead, the companies that make these new treatments actually pay you money for your time and travel costs.