Apoptosis is a genetically regulated, energy dependent process of cell death. More specifically, the cell destroys itself through membrane blebbing, condensation of chromatin, and fragmentation of DNA followed by swift phagocytosis of the corpse by adjacent cells. Apoptosis is triggered by the presence of specific stimuli, such as DNA damage, and is an essential part of cellular physiology. It can prevent cancers, and if apoptosis unexpectedly is not initiated, it may lead to tumor growth in the body. 

The mechanism of apoptosis is that it occurs during shrinking of the cytoplasm followed by the condensation of the nucleus. Apoptosis is dependent on caspase activation, leading to substrate cleavage and cellular death. It is also localized to destroy only a selection of individual cells, unlike necrosis. Apoptosis also plays a role in several biological processes such as aging, embryogenesis, and various diseases.