Immune checkpoints are regulatory pathways in the immune system that help maintain self-tolerance and prevent excessive immune responses. They are proteins found on the surface of immune cells, such as T cells, that can either enhance or inhibit immune responses. By doing so, immune checkpoints play a crucial role in preventing autoimmune diseases and ensuring that the immune system does not attack the body's own tissues. In cancer therapy, immune checkpoints have gained attention because some tumors exploit these pathways to evade detection by the immune system. Checkpoint inhibitors, a type of cancer treatment, block these proteins, allowing the immune system to recognize and attack cancer cells more effectively. This approach has shown promise in treating various types of cancer, including melanoma and lung cancer.