Smart contract code on monitor with solidity syntax highlighted

Solidity smart contracts, the dominant language on Ethereum, revolutionize self-executing agreements with immutable and transparent code.

About this subject

Solidity is a contract-oriented programming language created in 2014 by Gavin Wood, co-founder of Ethereum, to write smart contracts on the Ethereum Virtual Machine (EVM). Since then, it has become the standard language for developing decentralized applications (dApps) on Ethereum and other EVM-compatible blockchains like Binance Smart Chain, Polygon, and Avalanche. Its syntax is inspired by C++, Python, and JavaScript, easing adoption by developers familiar with those languages.

Smart contracts are self-executing code that, once deployed on the blockchain, cannot be altered, ensuring transparency and trust without intermediaries. They are used in various fields: decentralized finance (DeFi), non-fungible tokens (NFTs), voting systems, supply chains, and insurance. Each contract is compiled into bytecode and stored on the blockchain, with a unique address. Execution is triggered by transactions, and each operation consumes gas, a fee paid in ETH to compensate miners or validators.

A major milestone was the launch of Ethereum in 2015, which popularized smart contracts. In 2016, the DAO hack exposed vulnerabilities in poorly written contracts, leading to a hard fork that created Ethereum Classic. Since then, security practices like audits and use of tested libraries have become essential. The latest version, Solidity 0.8.x, introduced automatic arithmetic overflow checks to prevent common bugs. Tools like Remix IDE, Hardhat, and Truffle simplify contract development, testing, and deployment.

Fun fact: the name Solidity has nothing to do with solids; it was chosen for sounding technical and trustworthy. The community maintains standards like ERC-20 (fungible tokens) and ERC-721 (NFTs), which are widely used contract implementations. With the growth of DeFi and NFTs, demand for Solidity developers has skyrocketed, making the language one of the most valuable in the tech job market.

Frequently Asked Questions

What is Solidity and what is it used for?

Solidity is a programming language for writing smart contracts on the Ethereum blockchain and other EVM-compatible blockchains. It enables creating self-executing contracts that run exactly as programmed, without censorship, fraud, or third-party interference.

What are the main applications of Solidity smart contracts?

They are used in decentralized finance (DeFi) for lending and exchanges, non-fungible tokens (NFTs) for digital art and collectibles, voting systems, supply chains, insurance, and any scenario requiring trustless agreements.

Which tools are used for Solidity development?

Key tools include Remix IDE (online), Hardhat and Truffle (development frameworks), and libraries like OpenZeppelin for secure and standardized contracts. Testing is done with tools like Mocha and Chai.