Lives on blockchain and cannot be changed after deployment.

Solidity (Ethereum)

• Solidity is the programming language for smart contracts on Ethereum

pragma solidity ^0.8.0;

contract SimpleStorage {
    uint public value;

    function set(uint _value) public {
        value = _value;
    }
}

Gas Fees

Gas = cost to run operations on blockchain

• Simple transfer → cheap
• Complex contract → expensive
• To:
  • prevent spam
  • pay validators

Gas fee = gas used × gas price

Contract Deployment

Deployment steps:

1. Write Solidity contract
2. Compile → bytecode
3. Send transaction to blockchain
4. Pay gas fee