Cell division is the process by which a parent cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukaryotes, there are two distinct types of cell division: a vegetative division (mitosis), producing daughter cells genetically identical to the parent cell, and a cell division that produces haploid gametes for sexual reproduction (meiosis), reducing the number of chromosomes from two of each type in the diploid parent cell to one of each type in the daughter cells. Mitosis is a part of the cell cycle, in which, replicated chromosomes are separated into two new nuclei. Cell division gives rise to genetically identical cells in which the total number of chromosomes is maintained. In general, mitosis is preceded by the S stage of interphase and is followed by telophase and cytokinesis; which divides the cytoplasm, organelles, and cell membrane of one cell into two new cells containing roughly equal shares of these cellular components. The different stages of mitosis all together define the M phase of an animal cell cycle—the division of the mother cell into two genetically identical daughter cells. To ensure proper progression through the cell cycle, DNA damage is detected and repaired at various checkpoints throughout the cycle. These checkpoints can halt progression through the cell cycle by inhibiting certain cyclin-CDK complexes. Meiosis undergoes two divisions resulting in four haploid daughter cells. Homologous chromosomes are separated in the first division of meiosis, such that each daughter cell has one copy of each chromosome. These chromosomes have already been replicated and have two sister chromatids which are then separated during the second division of meiosis. Both of these cell division cycles are used in the process of sexual reproduction at some point in their life cycle. Both are believed to be present in the last eukaryotic common ancestor.

The cell is the basic structural and functional unit of all forms of life. Every cell consists of cytoplasm enclosed within a membrane; many cells contain organelles, each with a specific function. The term comes from the Latin word cellula meaning 'small room'. Most cells are only visible under a microscope. Cells emerged on Earth about 4 billion years ago. All cells are capable of replication, protein synthesis, and motility.