Blockchain (区块链) is a digital ledger technology that records data across many computers in a way that makes it nearly impossible to alter or hack. The word breaks down literally as 'district' (区), 'block' (块), and 'chain' (链): each 'block' stores a batch of verified transactions, and these blocks are cryptographically linked into a secure, chronological 'chain'. Unlike traditional databases controlled by a central authority, blockchain is decentralized and transparent—any participant can verify the data, but no single party owns or controls it.

This term is widely used in finance (e.g., cryptocurrencies like Bitcoin), supply chain management, identity verification, and smart contracts. While the concept is technical, 区块链 itself functions as a standard noun in Chinese—often used without modification, and frequently appears with modifiers like '技术' (technology), '平台' (platform), or '应用' (application). It’s a loanword adapted directly from English but fully integrated into modern Mandarin vocabulary.