What Is a Seed Phrase, and Why You Should Never Share It

Macro close-up of a paper card with twelve numbered handwritten lines (illegible scribbles), with an old-fashioned brass key resting across it.

When you set up a crypto wallet, you are given a list of words. Usually twelve. Sometimes twenty-four. This is called a seed phrase, or recovery phrase. That list of words is the master key to everything in your wallet. Anyone who has it can access your crypto from any device, anywhere in the world, instantly.^[1] If you lose it, your crypto may be unrecoverable. If someone else gets it, your crypto is gone.

There is a phrase in the crypto world that captures this exactly: not your keys, not your crypto. If you do not control your seed phrase, you do not truly own what is in your wallet. In 2025, the FBI recorded over $11 billion in cryptocurrency-related losses.^[2] A large proportion trace back to one of two things: a stolen seed phrase, or a fake platform. This module covers both.