What is a Blockchain?

A blockchain is a decentralized digital ledger that records transactions across a network of computers. Instead of being stored in one central place, data is grouped into blocks and linked chronologically using cryptography.

This structure makes records transparent, secure, and nearly impossible to alter, forming the foundation of cryptocurrencies and many other decentralized applications.


A blockchain is a distributed database shared across a network of computers (nodes). Instead of relying on a central authority like a bank, participants collectively validate and record transactions through a consensus mechanism such as Proof of Work or Proof of Stake.

Each transaction is stored in a “block.” Once verified, the block is cryptographically linked to the previous one, forming a continuous “chain.” This linkage makes past records extremely difficult to change without network approval.

Blockchains are transparent (transactions can be publicly viewed), immutable (hard to alter), and secure (protected by cryptography). Beyond cryptocurrencies like Bitcoin and Ethereum, blockchain technology powers smart contracts, decentralized finance (DeFi), NFTs, supply chain tracking, digital identity systems, and voting platforms.

In simple terms, blockchain replaces trust in institutions with trust in code and distributed consensus.