Cytokinesis in animal cells involves creating a contractile ring that pinches inwards, eventually splitting the cell in half. Cytokinesis begins in the anaphase (beginning of nuclear division) and continues until telophase (separation of genetic material).
Cytokinesis is an essential part of the cell division process because it ensures that the nucleus is divided evenly between the daughter and parent cell. In animal cells, cytokinesis begins as a ring of protein filaments that develops under the plasma membrane that surrounds the equator of the parent cell. As the ring contracts, it creates a dip in the cell called a cleavage furrow. The ring will continue to contract until the cell is divided into two with each cell supported by its own plasma membrane. The process of cytokinesis is especially important during telophase, when genetic material is divided between the cells.