Blockchain

The public ledger of every Bitcoin transaction, organised into a chain of blocks.

The Bitcoin blockchain is the complete history of every transaction ever made on the network, stored as a chain of blocks. It is public — anyone with the software can download it, read it, and verify it. It is append-only — you can add new blocks but you cannot edit old ones without invalidating everything after.

The chain part matters. Each block contains a hash (a fingerprint) of the block before it. Change a transaction in an old block and the hash changes; that breaks the link to the next block, which breaks every block after. Rewriting history would require redoing all the proof-of-work since that point — economically impossible.

The blockchain is what makes Bitcoin trustworthy without a central authority. You don't have to trust me, or BTCBitByBit, or any exchange — you can run your own node and verify the entire ledger from scratch.

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Course topic

Mining & nodes

How Bitcoin actually works. Miners, nodes, blocks, and what running your own changes.

Course topic

Bitcoin foundations

Start here. What Bitcoin is, where it came from, and why it matters.

Related terms

Glossary

Block

A bundle of Bitcoin transactions added to the blockchain roughly every ten minutes.

Glossary

Mining

The process of competing to add new blocks to the Bitcoin blockchain. Miners earn block rewards plus fees.

Glossary

Node

A computer running Bitcoin software that stores and verifies the entire blockchain.

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