Apoptosis is a form of cellular suicide. The process is also known as programmed cell death. This is one of those rare instances where the death of a cell benefits the organism as a whole.

Apoptosis is a normal and necessary part of development. As the human body develops, it becomes necessary to get rid of or kill certain cells. This could be due to several different reasons. These are just a few of many instances that demonstrate when and why apoptosis occurs.  

• Some cells may be malignant and could damage the rest of the organism if they survive. Cells with DNA damage or viral infections are two such examples. In this case, apoptosis benefits the organism by eliminating potentially virus-infected and cancerous cells.
• In other cases, some cells may need to be eliminated to carve out various structures that make up part of the human body. For example, the hand starts out as a large block of tissue within the embryo. The fingers are carved out of this block by apoptosis of the cells between the developing digits.
• In adult organisms, apoptosis occurs to remove cells that are required only for temporary tasks and make way for new, more useful cells.

During the process of apoptosis, the cells commit suicide spontaneously after receiving certain cues. The contents of the dead cell are packaged into tiny membrane packets, which are then collected and eliminated by immune cells.  

Apoptosis is different from necrosis in which the cells die due to an adverse external force such as infection, poisoning, or bodily injury.