Photodynamic therapy uses light-activated photosensitizing compounds and oxygen to kill targeted malignant and diseased cells. It has three key components: a light source, photosensitizer, and molecular oxygen. The photosensitizer is administered and absorbs light, generating reactive oxygen species that destroy nearby cells through apoptosis or necrosis. PDT has advantages of being minimally invasive, toxic, and allowing short recovery times compared to other treatments like surgery or chemotherapy. However, it is not suitable for all cancer types and can cause temporary skin sensitivity to light. Research continues to expand its applications and availability.