In a smart contract, every transaction would be implemented without the interference of a third-party or middlemen.
Simply put, a smart contract is a legal agreement in the form of a computer program that executes itself when particular conditions are met. These conditions are what all parties involved have already agreed upon. Once deployed or put into action, a smart contract cannot be interfered with.
For decades though, smart contracts remained hardly more than an intriguing hypothesis.
It was extremely difficult to write a secure, efficient program that could store the terms of an agreement, verify its outcomes and then complete the transaction without human interference.