Smart Contract

A smart contract is a program deployed on a blockchain that executes automatically when specific conditions are satisfied. Unlike traditional contracts that rely on intermediaries like lawyers or banks, smart contracts enforce rules through code, removing the need for trust between parties.

How Smart Contracts Work:

1. A developer writes the contract logic in a programming language (e.g., Solidity for Ethereum)
2. The compiled code is deployed to the blockchain and assigned an address
3. Users interact with the contract by sending transactions
4. The blockchain network executes the code and updates state accordingly
5. Results are recorded permanently on-chain

Common Use Cases: - DeFi Protocols: Lending, borrowing, and trading without intermediaries - Token Creation: ERC-20, ERC-721 (NFT), and other token standards - DAOs: Governance voting and treasury management - Insurance: Automatic payouts based on verifiable events - Supply Chain: Tracking goods and triggering payments on delivery

Key Properties: - Deterministic: Same inputs always produce the same outputs - Immutable: Once deployed, the code cannot be changed (unless designed with upgrade patterns) - Transparent: Anyone can read the code and verify its behavior - Trustless: No need to trust a counterparty

Limitations: - Cannot access off-chain data without oracles - Bugs in code can lead to significant financial losses - Gas costs can make complex operations expensive - Immutability makes fixing vulnerabilities difficult

Notable smart contract exploits, such as the 2016 DAO hack ($60M) and the 2022 Wormhole bridge exploit ($320M), highlight the importance of thorough auditing before deployment.