Autophagy is a conserved cellular process that enables cells to recycle nutrients and remove damaged components. It plays a critical role in both innate and adaptive immunity by degrading intracellular pathogens, delivering antigens to MHC class II compartments, and regulating T-cell homeostasis. Autophagy is essential for the removal of intracellular bacteria, parasites, and viruses, and it also contributes to the presentation of viral antigens to the immune system. The process involves the formation of autophagosomes, which fuse with lysosomes to degrade the contents. Autophagy is regulated by various signaling pathways, including mTOR and PI3K, and can be induced by amino-acid starvation or growth-factor withdrawal. Recent studies have shown that autophagy is involved in the clearance of intracellular pathogens, the regulation of immune responses, and the prevention of autoimmunity. Autophagy also plays a role in the presentation of viral antigens to MHC class II molecules, which is crucial for adaptive immunity. The regulation of autophagy by immune signals, such as IFNγ and TNF, is important for the control of infections. Autophagy is also involved in T-cell homeostasis, with excessive autophagy leading to the death of effector T cells. Additionally, autophagy is linked to the prevention of inflammation and autoimmunity by ensuring the proper clearance of apoptotic cells. Overall, autophagy is a key player in immune defense and homeostasis, with implications for a wide range of diseases, including cancer, neurodegenerative disorders, and autoimmune diseases.Autophagy is a conserved cellular process that enables cells to recycle nutrients and remove damaged components. It plays a critical role in both innate and adaptive immunity by degrading intracellular pathogens, delivering antigens to MHC class II compartments, and regulating T-cell homeostasis. Autophagy is essential for the removal of intracellular bacteria, parasites, and viruses, and it also contributes to the presentation of viral antigens to the immune system. The process involves the formation of autophagosomes, which fuse with lysosomes to degrade the contents. Autophagy is regulated by various signaling pathways, including mTOR and PI3K, and can be induced by amino-acid starvation or growth-factor withdrawal. Recent studies have shown that autophagy is involved in the clearance of intracellular pathogens, the regulation of immune responses, and the prevention of autoimmunity. Autophagy also plays a role in the presentation of viral antigens to MHC class II molecules, which is crucial for adaptive immunity. The regulation of autophagy by immune signals, such as IFNγ and TNF, is important for the control of infections. Autophagy is also involved in T-cell homeostasis, with excessive autophagy leading to the death of effector T cells. Additionally, autophagy is linked to the prevention of inflammation and autoimmunity by ensuring the proper clearance of apoptotic cells. Overall, autophagy is a key player in immune defense and homeostasis, with implications for a wide range of diseases, including cancer, neurodegenerative disorders, and autoimmune diseases.