Qtum
Qtum is a decentralized, open-source blockchain platform designed specifically to bridge the gap between Bitcoin's blockchain and Ethereum's smart contracts. It was developed by a team from both China and the United States and was launched in early 2017.
The Qtum platform uses a hybrid consensus algorithm known as "Proof-of-Stake" (PoS) which combines the security of Bitcoin's Proof-of-Work (PoW) system with the efficiency and affordability of Ethereum's PoS system. In addition, Qtum's blockchain uses a "Decentralized Governance Protocol" (DGP) which allows changes to be made to the network through community consensus.
The goal of Qtum is to make it easier and more efficient for developers to create decentralized applications (dApps) and smart contracts using a familiar programming language (e.g. Solidity) while also ensuring the security and scalability of the network. Qtum's unique features have made it an attractive option for businesses and individuals looking to build blockchain-based applications.