The cell cycle is divided into several phases:
M - mitosis - the process of nuclear division, and formation of two daughter cells.
G1 - phase between the end of mitosis, and the beginning of DNA synthesis (Growth phase 1)
S - replication of nuclear DNA (S - synthesis)
G2 - phase between the end of DNA synthesis and the start of mitosis (Growth phase 2)
The length of the cell cycle varies from cell to cell. Commonly it is around 24 hours. However, some cells 'arrest' in G1 for long periods of time - up to one year!