Basics

Start here: the ideas everything else builds on.

• What is Bitcoin?

  Digital money that works without banks, run by thousands of computers following the same rules.

• Blockchain

  A public record where each new page is locked to the one before it.

• Block

  A batch of transactions sealed into Bitcoin's history about every ten minutes.

• Transaction

  A signed instruction that moves bitcoin from your addresses to someone else's.

• UTXO

  Bitcoin's version of cash: your balance is a pile of spendable chunks, not a number.

• Keys & addresses

  A secret number that spends your bitcoin, and the public label people pay you at.

• Seed phrase

  Twelve or twenty-four words that can rebuild your entire wallet anywhere.

• Confirmation

  How deeply buried your transaction is — each new block makes it harder to reverse.

• The double-spend problem

  The problem Bitcoin solved: stopping digital money from being copied and spent twice.

• Satoshi (the unit)

  The smallest piece of a bitcoin — one hundred-millionth, named after its creator.

• Fork (concept)