Radiation therapy, also known as radiotherapy, is a medical treatment that uses high-energy radiation to target and destroy cancer cells or to prevent their growth. This form of treatment is commonly used to treat various types of cancer. It works by damaging the DNA of cancer cells, which prevents them from dividing and growing further. Radiation therapy can be administered externally, where a machine directs radiation beams towards the affected area, or internally, by placing a radioactive source near or inside the tumor. The goal of radiation therapy is to eliminate or shrink the cancer while minimizing damage to surrounding healthy tissues. It is often used in conjunction with other cancer treatments, such as surgery or chemotherapy, to provide a comprehensive approach to cancer care.