The key to blockchain technology lies in smart contracts, which can automatically execute contract terms without intermediary intervention, changing the way multiple industries operate. Smart contracts evolved from early concepts to implementation on Ethereum, featuring immutability and traceability. Their applications are wide-ranging, including democratic voting, supply chain management, insurance claims, and more, but they also face technical risks, legal vacuum, and cost issues. In the future, smart contracts are expected to become important tools for financial and business operations.