Smart contracts are self‑executing agreements written in code and deployed on blockchain networks. They run automatically when predefined conditions are met. Ethereum is the most popular platform for smart contracts, but alternatives such as Solana, Cardano, and Hyperledger are also used.

Developers write smart contracts using languages like Solidity. They must consider gas fees, security vulnerabilities, and upgrade strategies. Smart contracts are used in decentralized applications (DApps), which allow users to interact directly with blockchain networks without intermediaries.

DApps support decentralized finance, gaming economies, intellectual property registries, and digital identity ecosystems. Designing and testing smart contracts requires careful validation to prevent security flaws. As adoption increases, demand for skilled blockchain and smart contract developers will grow across startups, enterprise innovation labs, and fintech organizations.