Qtum is a smart contract platform that uses a Proof-of-Stake (PoS) consensus mechanism to validate transaction blocks and provide security assurances. It uses Bitcoin core as the base of its network for security and stability reasons and thus operates via a UTXO model. The project has also integrated Ethereum's virtual machine (the EVM) so that the chain can run Turing complete code needed to support smart contracts and decentralized applications (dApps). Qtum's stack includes a middleware layer, called the Account Abstraction Layer (AAL), to ensure compatibility between the UTXO set and the smart contract execution layer. The Qtum native token (QTUM) allows users to pay transaction fees, participate in network security, and vote on protocol upgrade proposals.