BIP39

The standard for generating a wallet from a 12 or 24-word seed phrase.

BIP-39 is the standard that defines how a wallet generates a seed phrase — those 12 or 24 words you write down on paper — and how that seed phrase is converted back into a wallet. It uses a fixed 2048-word dictionary; every BIP-39 word is unique enough that you can't confuse one for another.

BIP-39's power is portability. A seed phrase generated by one BIP-39 wallet can be imported into any other BIP-39 wallet. That means your seed phrase is not tied to BTCBitByBit, or to any specific software — it is the master key to your money, recoverable in any compatible app, on any device, forever.

The 2048-word dictionary also means typos are usually catchable. If you write down "abundant" instead of "abandon", a BIP-39 wallet will reject the seed phrase rather than silently load a different wallet. The checksum built into BIP-39 catches most single-word errors.

ExampleA BIP-39 seed phrase: "abandon ability able about above absent absorb abstract absurd abuse access accident".

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Related terms

Glossary

Seed phrase

A 12 or 24-word phrase that backs up your entire wallet. Lose it, lose your sats. Share it, lose your sats.

Glossary

BIP

Bitcoin Improvement Proposal — the standard format for proposing changes to Bitcoin.

Glossary

Private key

The cryptographic secret that authorises spending Bitcoin. If someone gets your private key, they can spend your sats.

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