Qtum

Qtum (pronounced Quantum) is a smart contract platform that uses a Proof-of-Stake (PoS) consensus mechanism to validate transaction blocks and provide security assurances. It combines different aspects of the Ethereum and Bitcoin blockchains. Qtum uses Bitcoin core as the base of its network for security and stability reasons and, therefore, operates via a UTXO model. The project also integrated Ethereum's virtual machine (the EVM) so the chain could run Turing complete code needed to support smart contracts, and thus decentralized applications (dApps). Qtum's stack features a middleware layer, dubbed the account abstraction layer (AAL), to ensure the UTXO set was compatible with the smart contract execution layer. Qtum's native token (QTUM) allows users to pay transaction fees, participate in network security, and vote on protocol upgrade proposals.