A blockchain is a type of distributed ledger that stores records in blocks linked with cryptographic techniques. It is a way to organise and share records. It is not a physical chain, a coin or a guarantee that anything connected with it is trustworthy.
Bitcoin provides a familiar example, but its rules should not be assumed to apply to every blockchain. Different networks can organise participation, validation and records in different ways.
Blocks and links
A block is a bundle of records. In Bitcoin, blocks contain transaction information. Each block includes a cryptographic reference to the previous block, which links the sequence together. The Bitcoin developer documentation describes this as an ordered and timestamped public record of transactions.
That linking has an important consequence: changing a transaction in an earlier recorded block would also require changing that block and the following blocks. This is part of Bitcoin’s design. It is not a reason to assume that every claim made about a blockchain, token or website is accurate.
Blockchain is a kind of distributed ledger
The FCA explains distributed ledger technology as a system for storing and managing information across participants in a network. It describes blockchain as the type of distributed ledger technology cryptoassets typically use, with information stored in cryptographically linked blocks.
The relationship is simple: distributed ledger is the broader idea; blockchain is one way to structure a distributed ledger. They should not be used as interchangeable labels for all digital systems.
What a blockchain record can show
A blockchain can record events according to the rules of a particular network. What that record means outside the network depends on the circumstances. A record does not, by itself, prove the identity of a person, the authenticity of a physical object, copyright ownership, legal title or value.
Bitcoin is an example, not the definition
Bitcoin’s blockchain records Bitcoin transactions. Ethereum and other networks have different technical purposes and rules. Describing one network accurately is not the same as making a claim about all blockchains.
For shorter definitions, see the crypto glossary. Read our separate guide to the difference between a distributed ledger and a blockchain for the category-and-subtype distinction.
Sources and scope
Sources: FCA Crypto: the basics; Bitcoin developer documentation on the block chain. This is a terminology guide, not financial, tax or legal advice. Source check: 15 September 2026. Corrections can be sent through The Coin Expert contact page.