This document discusses thermal storage and hybridization for solar thermal power plants. It covers various thermal storage technologies used in commercial concentrated solar power installations, including short-term pressurized water storage and mid-term molten salt storage using both direct and indirect systems. Research and development areas are also reviewed, such as thermocline storage, phase change materials, and fluidized bed storage using sand. The benefits of thermal storage and hybridization are outlined, including facilitating dispatchability and improving plant utilization and capacity factors. Simulation results are presented comparing the operation of solar-only and hybrid plants.