Cell cycle checkpoints are critical control mechanisms in the cell cycle that ensure the proper progression of cell division. They monitor the integrity of the cell's DNA and the completion of essential processes before allowing the cell to move to the next phase. There are three main checkpoints: the G1 checkpoint, the G2 checkpoint, and the M checkpoint. At each checkpoint, the cell assesses whether conditions are favorable for division. If issues are detected, such as DNA damage or incomplete replication, the cell can pause the cycle to repair the damage or, if necessary, initiate apoptosis, or programmed cell death, to prevent the propagation of errors.