Smart Contracts

Smart contract is a program deployed on a blockchain. When a user transaction comes in that matches the defined rules, it runs exactly as the code dictates. You can write things like token transfer rules, NFT mint rules, lending rules, and marketplace escrow rules as smart contracts.

You could call a smart contract "a contract turned into code," but it isn't automatically the same thing as a legal contract out in the real world. If there's a bug in the code, it can lead to asset loss, and fixing a contract after it's deployed can be difficult. You need to think security-first about things like audits, testing, permission design, emergency pause mechanisms, and upgrade patterns.

// Simple idea only, not production code
contract SimpleVault {
  mapping(address => uint256) balances;

  function deposit() public payable {
    balances[msg.sender] += msg.value;
  }

  function withdraw(uint256 amount) public {
    require(balances[msg.sender] >= amount, "Not enough balance");
    balances[msg.sender] -= amount;
    payable(msg.sender).transfer(amount);
  }
}

A smart contract can give you trustless automation, but a single bug can cause a real loss of money.