The control and operation of future smart grids should handle complex multi-objective regulation optimization problems characterized by a high degree of diversification in policies, strategies, and widely distribution in demand and supply sources. In this lecture, after an introduction on smart grids, some important challenges on control and operation are explained. The important role of smart monitoring, energy management system (EMS) and supervisory control and data acquisition (SCADA) center are emphasized, and the reasons behind using of intelligent/smart techniques in modern electric grids are described. In comparison of the conventional power grids in which the synchronous machines dominate, the future smart grids use numerous microgrids with distributed generators (DGs). With growing the penetration level of DGs, which have either very small or no rotating mass and damping property, the impact of low inertia and damping effect on the grid stability/control and dynamic performance increases. In this speech, a discussion on microgrid control issues, including main concepts, classifications, and new results is also presented.