Here's a breakdown:

* Cytokinesis: The process of dividing the cytoplasm of a cell, which occurs after nuclear division (mitosis or meiosis).

* Cleavage furrow: A shallow groove on the cell surface that gradually deepens, eventually pinching off the cell into two daughter cells.

This is in contrast to plant cells, where cytokinesis involves the formation of a cell plate which grows inward from the cell wall to divide the cell.