Some cells in an adult animal do not divide, e.g., nerve cells, whereas many cells divide occasionally just to replace the cell loss due to injury or cell death. Such type of cells remains in $G _{0}$ phase.
The $G _{0}$ phase of the cell cycle is also known as the quiescent stage. In this phase, the cell remains metabolically active but does not proliferate unless they are called on to do so.
Cells in $G _{0}$ phase of the cell cycle, suspend the cell cycle for some time but do not fully terminate the cell cycle.