Blockchain

A blockchain is a type of digital record-keeping system, first popularized by Bitcoin. It works as a chain of blocks, with each block holding data—usually records of transactions, such as someone sending bitcoin to another person.

Picture a blockchain like an online ledger open to everyone. Every block acts as a new page in this ledger, recording recent activity and updating all balances in the network. What sets blockchain apart is that instead of being stored in one place, copies are shared and synchronized across thousands of computers (called nodes), making it decentralized and visible to anyone.

A defining feature of blockchains is their immutability. Once a block’s data is added and confirmed, it becomes extremely difficult to modify. Each new block builds on the last, which ensures that the record of past transactions remains secure and unchangeable.