What is the difference between initial and final setting time of cement?

Initial setting time is when cement paste starts to lose plasticity and begins to stiffen (minimum 30 minutes for OPC). Final setting time is when cement has hardened sufficiently to sustain load without damage (maximum 600 minutes for OPC). These are measured using Vicat apparatus. Setting times are important for concrete placement - initial setting determines available working time, while final setting determines when finishing operations and curing should begin.