Seed Phrase
In short: A seed phrase is the recovery phrase for a crypto wallet: a list of ordinary words, most often 12 or 24, that encodes the master secret from which the…
A seed phrase is the recovery phrase for a crypto wallet: a list of ordinary words, most often 12 or 24, that encodes the master secret from which the wallet generates its private keys. Anyone who has the phrase can restore the wallet, and every asset in it, in a compatible wallet app.
Why it matters
The seed phrase is the ultimate backup, so if a phone breaks or a hardware wallet is lost, entering the phrase into a new wallet restores access. For the same reason it must stay secret, because a stolen seed phrase means stolen funds. Keep it offline, for example written on paper or stamped into metal in a safe place, and never type it into a website, share it in a chat, or save it as a photo or cloud note. No legitimate support team will ever ask for it.
Example
When you create a new self-custody wallet, the app shows a list of words and asks you to write them down in order, then confirm a few of them. Later, your phone stops working. You install the same wallet app on a new phone, choose the restore option, enter the words in the same order, and your addresses and balances reappear.