Seed Phrase

A seed phrase is a list of 12 to 24 ordinary words that is the master backup for a crypto wallet. From it, the wallet can regenerate every private key it controls, so the phrase alone can restore your entire self-custody wallet on a new device. It is also called a recovery phrase or mnemonic.

The words are not random labels. They come from a standard list of 2,048 words (the BIP-39 standard), and their exact order encodes the number that seeds your keys. Enter the same words in the same order into a compatible wallet and you recover the same addresses and assets. Change one word or the order and you get a different, empty wallet.

This design is what makes self-custody usable: instead of backing up a long, error-prone string of characters for every key, you safeguard one human-readable phrase. When you set up a wallet, it shows you the phrase once and asks you to write it down.

The phrase is also the single biggest risk you carry. Anyone who sees it can recreate your wallet and drain it, from anywhere, with no way to reverse the theft. So the rules are strict: write it on paper or metal, store it offline, never type it into a website or share it with "support," and never photograph it or save it in cloud notes - that is how most wallet thefts happen.

For larger holdings, a hardware wallet generates the seed phrase on the device itself, so it is never exposed to an internet-connected computer. If you hold tokenized real-world assets in self-custody, this phrase is what protects them.

Source: Ethereum docs (ethereum.org), as of 2026.