Apoptosis refers to a particular form of cell death or cell suicide in which a sequence events that are preprogrammed lead to cell elimination without releasing harmful substances into the surrounding cell spaces.
This process plays an important role in developing and maintaining health by eliminating old cells, unnecessary cells, and unhealthy cells. Too little or too much apoptosis plays a role in a great many diseases.
When programmed cell death becomes aberrant cells that should be eliminated may become immortal. For example, in a cancer like leukemia. When apoptosis is excessive it kills too many cells and can inflict cellular damage.