Block

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

A block is a batch of recent Bitcoin transactions that miners compete to add to the blockchain. Roughly every ten minutes, one miner wins the lottery, their candidate block is broadcast to the network, and every node validates and adds it to the chain.

Each block contains the transactions, a reference to the previous block (which is what makes it a chain), a timestamp, the miner's reward transaction, and a number called a nonce that proves the miner did the proof-of-work. The whole package is around 1-2 MB.

Once a transaction is in a block, it has one confirmation. Each subsequent block adds another confirmation. Most exchanges consider a transaction "settled" after six confirmations — about an hour. For everyday payments, especially via Lightning, you don't wait for confirmations at all.

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Related terms

Glossary

Blockchain

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

Glossary

Mining

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

Glossary

Mempool

The waiting room of unconfirmed transactions — where every Bitcoin transaction sits before being included in a block.

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