Smart Contract

A smart contract is a piece of program which runs on the blockchain and its execution is examined and enforced by the relevant consensus protocol. Smart contract is a special protocol designed to contribute, verify or implement the negotiation or performance of the contract [9]. Smart contracts allows automatic execution of transactions without any supervision from third parties. Users invoke a smart contract in present cryptocurrencies by sending transactions to the contract address deployed on the blockchain. Transactions sent by the user to the blockchain will cause a state change that will be reflected in the change of account balance or the state value of the contract.

These transaction calls to the smart contract are traceable and immutable, and they can be verified by any participants in the blockchain network.