Quick answer
A blockchain is an ordered, shared record of state changes grouped into linked blocks.
What is Blockchain?
A blockchain is a data structure and coordination system in which participants agree on an ordered history of transactions or other state changes. Different networks use different rules for validation, consensus, and finality.
The useful way to approach this term is to separate its definition from the assumptions people often attach to it. In crypto, the same word can appear in a protocol rule, a user interface, a market-data label, or a marketing claim. Check which layer the explanation is describing.
Why does blockchain matter?
The word is often used as if every chain works the same way. Checking the actual network, consensus model, upgrade process, and finality assumptions is more useful than relying on the label alone.
Concrete example
See it in a real situation
A block may contain transactions, a reference to the previous block, a timestamp, and consensus-specific data. Nodes validate the block before extending their view of the chain.
Common misconceptions
What this term does not mean
- A blockchain is not automatically decentralized just because it uses blocks.
- Putting data on a blockchain does not make the data private or correct by itself.
Related terms
Sources and further reading
Definitions are written for education and checked against the sources below where relevant. A source can explain a protocol or rule without endorsing every product built around it.