T cell tolerance refers to the ability of the immune system to recognize and tolerate self-antigens, preventing the immune system from attacking the body's own cells and tissues. This process is crucial for maintaining immune homeostasis and preventing autoimmune diseases. T cell tolerance can occur through various mechanisms, such as central tolerance in the thymus where T cells are educated to recognize self-antigens as harmless, and peripheral tolerance where regulatory T cells suppress the activation of autoreactive T cells. Understanding the mechanisms of T cell tolerance is important for developing therapies for autoimmune diseases and improving transplantation outcomes.