Cell death is the event of a biological cell ceasing to carry out its functions. It may be due to the natural process of old cells dying and being replaced by new ones, or may result from such factors as disease, localized injury, or the death of the organism of which the cells are par.
The rate of death and the rate of cell birth by division, are both responsible for the size of the tissue, and also for the number of cells present in a tissue.
Cell death can largely be divided into 2 main categories:
Apoptosis represents active cell death.
Necrosis shows passive cell death with no underlying mechanism.