Blockchain technology is the distributed ledger system introduced alongside Bitcoin to track and verify transactions and prevent double spending. The Bitcoin blockchain is distributed across Bitcoin nodes — individual computers that run the protocol. The data in the blockchain are collected in “blocks” and they are cryptographically linked together in a chain so that, as transactions are buried in the blockchain, they cannot be altered without changing the rest of the data that has been verified on top of it as well. This data is verified automatically at certain intervals.
Because the Bitcoin blockchain is distributed across thousands of individual computers, there is no single “point of failure” or source that controls the network. Rather, it is decentralized across many nodes.
Like Bitcoin, blockchain technology was first introduced by Satoshi Nakamoto. But the technology has now been adopted by many different groups and companies for a wide range of use cases that involve maintaining a distributed ledger.