Macroautophagy/autophagy is an evolutionarily conserved cellular degradation process that targets cytoplasmic materials including cytosol, macromolecules and unwanted organelles. The discovery and analysis of autophagy-related (Atg) proteins have unveiled much of the machinery of autophagosome formation. Although initially autophagy was regarded as a survival response to stress, recent studies have revealed its significance in cellular and organismal homeostasis, development and immunity. Autophagic dysfunction and dysregulation are implicated in various diseases. In this review, we briefly summarize the physiological roles, molecular mechanism, regulatory network, and pathophysiological roles of autophagy.