The smart grid is much automated from which it can be integrated the main supply with distributed generation (DG) sources (mostly renewable), the energy storage systems (ESSs), and advanced metering infrastructure. Due to using high technology devices in generation and distribution systems, the smart grid represents an advanced digital system. For example, the power flow in two ways, adaptable, sustainable, self-healing, and flexible with the prediction under various uncertainties. This review paper gives a brief idea of the smart grid by highlighting smart grid definitions, a comparison of smart grid versus traditional grid, the attributes and benefits of smart grids, smart grid architecture, smart grid applications, and the challenges to smart grid implementation.