To build a smart contract, you typically use Solidity, the most popular programming language on Ethereum. You define your contract structure, variables, and functions. Tools like Remix IDE allow you to code, test, and deploy directly in the browser. Once deployed to the blockchain, the contract becomes a permanent part of it and can be interacted with by users or dApps.

Example in Video: A basic contract can store a user’s name and allow them to update it, demonstrating how to handle inputs, outputs, and storage in Solidity.