The process of cell division.
This is the longest stage. During this time the cell increases in size, and prepares to divide. It is what happens prior to mitosis and begins after that particular cell was split from the other daughter cell.
Prophase is the first stage of mitosis. The chromosomes begin to appear as duplicated chromotids. The nucleolus also disappears as the nucleus prepares for division. The centrioles go to the opposite poles and microtubules form between them. The disappearance of the nuclear envelope signals the next sub stage, and then meta-phase.
The chromosomes are coiled and the centrosomes are at opposite sides of the poles. The chromosomes are arranged in a line equidistant from the two poles called the metaphase plate.
The sister chromotids divide and the chromosomes move to the opposite poles, which involves the spindle. At the end of this stage two complete chromosomes are formed.
New nuclear envelope membrane forms and the chromosomes assemble at the poles. They also begin to uncoil and go to the same state as they were in interphase. The nuclear division is complete at this point.
This stage is the division of the cytoplasm, which usually starts at the end of telephase. In animal cells it is known for forming the cleavage furrow. Sometimes cytokinesis does not occur after nuclear division.