This paper analyzes the need and benefits of energy storage in electrical grids. Energy storages introduce many advantages such as balancing generation and demand, power quality improvement, smoothing the renewable resources. Hybrid energy storage systems characterized by coupling of two or more energy storage technologies are emerged as a solution to achieve the desired performance by combining the appropriate features of different technologies. Thus, a brief overview on energy and power storage technologies and devices is presented, including proposed models and specific characteristics and highlighting the benefits of hybridization based on the simulation results of energy storage systems.