Photodynamic therapy (PDT) is a minimally invasive medical procedure that uses a photosensitizing agent, light of a specific wavelength, and oxygen to selectively destroy abnormal cells. The photosensitizer is activated by light, producing reactive oxygen species that damage target tissues. PDT is employed in the treatment of various cancers, dermatological conditions like actinic keratosis, and certain infections, offering a targeted approach with reduced systemic side effects.