Apoptosis, or programmed cell death, is an internally controlled suicide program where cells are removed with minimal disruption of surrounding tissue. It plays important roles in development, tissue homeostasis, and defense against infection and cancer. There are two main apoptotic pathways - the intrinsic mitochondrial pathway and the extrinsic death receptor pathway. Both pathways activate caspases, cysteine proteases that cleave proteins to execute the cell death program through processes like DNA fragmentation and formation of apoptotic bodies. Deregulation of apoptosis contributes to cancer development by allowing damaged or unnecessary cells to survive. Targeting the apoptotic pathway is a strategy for cancer treatment.