Ethereum

Ethereum is a decentralized blockchain platform that extends the concept of a distributed ledger beyond simple transactions to support smart contracts, which are programs that execute automatically when predefined conditions are met. This programmability enables building decentralized applications that run on the blockchain without intermediaries or central control.

Smart contracts on Ethereum are typically written in Solidity, a purpose-built programming language, and deployed to the Ethereum Virtual Machine where they execute deterministically across all network nodes. Once deployed, a smart contract code cannot be changed, providing trustlessness but meaning bugs can be costly and irreversible. The network transitioned from proof-of-work to proof-of-stake in 2022, significantly reducing energy consumption.

For web development, Ethereum is relevant because it underpins the Web3 ecosystem including decentralized finance protocols, NFT marketplaces, and token-gated applications. Building web interfaces for Ethereum applications involves connecting to user wallets through libraries like ethers.js or wagmi, reading on-chain data, and submitting transactions. The developer tooling includes Hardhat and Foundry for local development. Understanding gas costs, confirmation times, and on-chain storage limitations is essential for usable Web3 interfaces.