What is the G0 phase in the cell cycle?

The G0 phase is a non-dividing, quiescent phase in the cell cycle where cells temporarily or permanently exit the cell cycle. During this phase, cells are metabolically active but do not undergo DNA replication, chromosome duplication, or cell division. The G0 phase is a state of cell cycle arrest or quiescence that cells can remain in for extended periods. The phase is essential for cellular differentiation, tissue maintenance, and repair.