The widespread use of distributed energy sources provides exciting potential for demand-side energy sharing and collective self-consumption schemes. Demand-side energy sharing and collective self-consumption systems are committed to coordinating the operation of distributed generation, energy storage, and load demand. Recently, with the development of Internet technology, sharing economy is rapidly penetrating various fields. The application of sharing economy in the energy sector enables more and more end-users to participate in energy transactions. However, the deployment of energy sharing technologies poses many challenges. This paper comprehensively reviews recent developments in demand-side energy sharing and collective self-consumption schemes. The definition and classification of sharing economy are presented, with a focus on the applications in the energy sector: virtual power plants, peer-to-peer energy trading, shared energy storage, and microgrid energy sharing cloud. Challenges and future research directions are thoroughly discussed.