This article presents a comprehensive guide to implementing smart contracts on blockchain networks, detailing their key features and historical development. It explores the automated execution and security advantages that smart contracts offer, while minimizing reliance on intermediaries. Readers will learn about the technical process of writing, compiling, deploying, and executing smart contracts across various blockchain platforms such as Ethereum, Gate, Solana, and Cardano. Additionally, the article highlights practical applications of smart contracts in DeFi, identity verification services, and decentralized trading, offering valuable insights for developers and innovators in blockchain technology.