Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells that have the ability to suppress immune responses. These cells play a critical role in regulating the immune system and maintaining immune homeostasis by inhibiting the activation and function of T cells, natural killer cells, and other immune cells. MDSCs are generated in response to various stimuli such as chronic inflammation, infection, and cancer. They are characterized by their ability to suppress immune responses through the secretion of immunosuppressive factors, induction of regulatory T cells, and inhibition of antigen presentation. Research on MDSCs has focused on understanding their role in promoting tumor growth and metastasis, as well as their potential as therapeutic targets for cancer immunotherapy. Additionally, studies have investigated the role of MDSCs in autoimmune diseases, chronic infections, and inflammatory disorders. Overall, research on MDSCs is aimed at elucidating their mechanisms of action, identifying biomarkers for their detection, and developing strategies to target and inhibit their immunosuppressive functions in order to enhance anti-tumor immunity and improve immune responses in various disease settings.