PSP (Pumped-storage power plants) represent the only mature option for large-scale electricity storage, and offer a wide range of grid management services, ranging from peak power production to ancillary services. This technology has undergone drastic progress in reliability, efficiency and generation capacity, with modern PSP being able to switch from pumping to generating mode in a few minutes and working at different levels of part load. This article presents a historical perspective and the current trends in PSP deployment at a global level. It covers initial investment rationale, the evolution of the operational management and trends in installed capacities, and a systematic overview on the contribution of PSP to electricity system flexibility and reliability to different electricity markets and different power grid configurations. Particular attention is devoted to the electricity production mix evolution in the selected countries. The role and operation of PSP have evolved significantly over time to adapt to new electricity mix and market conditions. Insights regarding the prospects and barriers of PSP in the coming decades are discussed, and estimates of remaining potential are compared with future storage needs, highlighting that alternative energy storage technologies will need to emerge alongside PSP to meet the future needs.