A PET scan, or Positron Emission Tomography scan, is a medical imaging technique that helps doctors observe metabolic processes in the body. It uses a small amount of radioactive material, called a tracer, which is injected into the bloodstream. The scan detects the radiation emitted by the tracer, allowing for the visualization of organs and tissues in real-time. This imaging method is particularly useful for diagnosing conditions such as cancer, heart disease, and brain disorders. By highlighting areas of increased or decreased activity, a PET scan can provide valuable information about the health and function of various body systems.