Solidity is a high-level, contract-oriented programming language used to write smart contracts that run on the Ethereum Virtual Machine (EVM). Developers use it to define the rules and behavior of decentralized applications (dApps), including how digital assets move, how permissions work, and how on-chain state changes over time.
How Solidity works on Ethereum and EVM chains
Solidity code is compiled into EVM bytecode, which is then deployed to a blockchain as a smart contract. Once deployed, the contract can be called by users or other contracts, and it executes deterministically across all nodes. Solidity uses curly-brace syntax and is influenced by languages like JavaScript, C++, and Python, which can make it approachable for many programmers. Because it targets the EVM, Solidity is used not only on Ethereum but also on EVM-compatible networks where the same contract logic can often be reused with minimal changes.
Common uses, from tokens to DeFi and NFTs
Many widely used crypto primitives are implemented in Solidity. For example, token contracts such as ERC-20 (fungible tokens) and ERC-721 or ERC-1155 (NFT standards) are commonly written in Solidity. DeFi protocols also rely on Solidity to implement lending pools, decentralized exchanges, staking, and governance, with contracts enforcing rules like collateral requirements or voting power. A typical real-world flow might involve a user approving a token spend, then calling a swap function on a decentralized exchange, both actions governed by Solidity code.
Security and why Solidity matters
Because smart contracts are difficult to change once deployed, Solidity development places heavy emphasis on security, testing, and audits. Bugs like reentrancy or integer errors can lead to loss of funds or broken application logic. Solidity matters because it is a foundational tool for building on-chain programs, and the safety, transparency, and reliability of much of the crypto ecosystem depends on how well these contracts are written.