A blockchain is a decentralized, distributed ledger that records transactions or data across a network of computers in a way that is transparent, secure, and nearly impossible to alter. Instead of relying on a single central authority, it uses a consensus mechanism—such as Proof of Work or Proof of Stake—to verify and add new transactions.
Each verified group of transactions is packaged into a block, time-stamped, and cryptographically linked to the block before it, forming an unbroken chain. This linkage ensures that once data is recorded, it cannot be changed without altering every subsequent block—making the system tamper-resistant.
Blockchains serve as the foundation of cryptocurrencies and decentralized finance (DeFi). They enable trustless systems, where participants can transact or share value directly without intermediaries. Beyond finance, blockchain technology supports applications in identity management, supply chains, digital ownership, and governance—representing a new model for recording and verifying truth in the digital age.