Solidity is the foundation of decentralized applications (dApps), enabling developers to write secure and efficient smart contracts for DeFi, NFTs, DAOs, and more. It is widely used for creating token standards like ERC-20 and ERC-721, ensuring interoperability in the Ethereum ecosystem. Understanding Solidity is crucial for blockchain developers aiming to build and audit smart contracts. Security best practices, such as preventing reentrancy attacks and optimizing gas efficiency, are essential for Solidity-based applications.