A smart contract is a computer program that tracks and enforces obligations. The parties prescribe in it the terms of the transaction and sanctions for their failure to comply, put digital signatures. A smart contract independently determines whether everything has been completed and makes a decision: complete the transaction and issue what is required (money, shares, real estate), impose a fine or penalty on participants, close access to assets. But when using this solution, you need to know what tools and knowledge are needed to start bug hunting in smart contracts https://hacken.io/education/how-to-smart-contracts-bug-hunting/ . This will be helpful to many people