Mitosis

Mitosis is the process in which a cell's nucleus replicates and divides in preparation for division of the cell. Mitosis results in two cells that are genetically identical. Mitosis is necessary for growth for repair and replacement of damaged or worn out cells.
All multi-cellular animals; plants, fungi, and protists, which begin life as single cells, carry out mitosis to develop into complex organisms containing billions of cells. Mitosis occurs in fully-grown organisms by maintaining it: replacing dying skin cells, for example or repairing damaged muscle cells. …