Regulatory T cells (Tregs) are a subset of T cells that play a crucial role in maintaining immune homeostasis and peripheral tolerance. They are specialized in suppressing or regulating immune responses, thereby preventing autoimmunity and excessive inflammation. Tregs are characterized by the expression of specific markers such as CD25, Foxp3, and CTLA-4, and they can be induced in the thymus as well as in the periphery. Research in the field of regulatory T cells focuses on understanding their mechanisms of action, differentiation pathways, and factors influencing their development and function. Additionally, studies are conducted to explore therapeutic strategies targeting Tregs for the treatment of autoimmune diseases, transplant rejection, and cancer. Overall, regulatory T cells are a critical component of the immune system with great potential for therapeutic applications in various diseases.