Cardano
An open-source permissionless blockchain platform built on the Ouroboros proof-of-stake protocol. Cardano was launched in 2017 to address issues with earlier blockchains such as high energy use, limited interoperability, and scalability challenges. Cardano is being developed in five phases: Byron (completed 2019), Shelley (decentralization, 2020), Goguen (smart contracts, 2021-), Basho (performance improvements, 2021-), Voltaire (treasury and governance, 2021-).