Smart contracts in blockchain is a prominent research area that focuses on self-executing code deployed on blockchain networks to automate agreements, transactions, and business logic without intermediaries. Smart contracts enhance transparency, trust, and efficiency by enforcing rules and conditions programmatically. Early research explored Ethereum’s Turing-complete smart contract platform and Solidity programming language, while later studies investigate formal verification, secure coding practices, gas optimization, and auditing techniques to prevent vulnerabilities and exploits such as reentrancy attacks. Recent advancements include cross-chain smart contracts, decentralized finance (DeFi) applications, non-fungible tokens (NFTs), IoT integration, and hybrid on-chain/off-chain execution frameworks for scalability and privacy. Applications span finance, supply chain management, healthcare, insurance, energy trading, and governance systems. Current research emphasizes security, formal verification, interoperability, performance optimization, and usability, establishing smart contracts as a core enabler of decentralized, autonomous, and trustless blockchain applications.