BIP-39
A standard for turning wallet backup data into a human-readable seed phrase, usually 12 or 24 words.
BIP-39 is a Bitcoin Improvement Proposal that defines how many crypto wallets create and read mnemonic seed phrases: the familiar list of 12, 18, or 24 words used to back up a wallet. The words are selected from a fixed word list and represent random data that can be converted into a seed for a hierarchical deterministic wallet, which can then generate many private keys and addresses. Although it began in the Bitcoin ecosystem, BIP-39 is widely used across many cryptocurrency wallets.
It matters because it gives users a portable backup format. If your phone is lost or your hardware wallet breaks, entering the same BIP-39 phrase into a compatible wallet can restore access to the same funds. A practical comparison is a master key: the phrase does not store coins itself, but it can recreate the keys that control them. Anyone who gets the phrase can usually access the wallet, so it should be written down accurately, kept offline, and never shared.
Other terms in Wallets & Security
Address Poisoning
A wallet scam where attackers plant lookalike addresses in your transaction history so you might copy the wrong recipient later.
Approval Phishing
A scam that tricks users into granting a malicious wallet or smart contract permission to spend tokens from their wallet.
Crypto Wallet
A tool that stores and manages the private keys needed to access and use cryptocurrency on a blockchain.
Custodial Wallet
A wallet where a third party, such as an exchange, holds the private keys and controls access to the crypto on your behalf.