Volunteers are essential to clinical trials. A patient volunteer (someone with a known health problem) can help researchers better understand, diagnose, treat, or cure that disease or condition. But healthy volunteers, who have no known major health problems, also play an important role in clinical research. They help researchers learn things that may indirectly help themselves and people they know. Both types of volunteers are needed, because researchers can learn more about a disease by comparing patient volunteers to healthy volunteers.

The purpose of clinical trials is research, so the studies follow strict scientific standards. These standards protect patients and help produce reliable study results.

Clinical trials are one of the final stages of a long and careful research process. The process often begins in a laboratory (lab), where scientists first develop and test new ideas.

If an approach seems promising, the next step may involve animal testing. This shows how the approach affects a living body and whether it's harmful. However, an approach that works well in the lab or animals doesn't always work well in people. Thus, research in humans is needed.

For safety reasons, clinical trials start with small groups of patients to determine whether a new approach causes harm. In later phases of clinical trials, researchers learn more about the new approach's risks and benefits.

Clinical trials are a key research tool for advancing medical knowledge and patient care. Clinical research is done only if doctors don't know

• Whether a new approach works well in people and is safe, and

• Which treatments or strategies work best for certain illnesses or groups of people.

Clinical trials help improve and advance medical care. They also can help health care decision-makers direct needed resources to the strategies and treatments that work best.