Seed phrase backup (metal backup)

The seed phrase restores every key in a wallet, so its backup is the real vault. The basic method is writing the 12 or 24 words by hand on the card that comes with a hardware wallet. Metal backups go further: words or their first four letters are stamped or engraved on steel or titanium plates, or assembled from letter tiles, so they survive fire and water far better than paper.

Where and how you keep the backup matters as much as the medium. Common practice is to store it away from the device, in a place you control, and to test recovery once with a small amount. Holders of larger sums often keep a second copy in another location, add a passphrase or use multisig or Shamir shares so that no single backup gives full access.

The classic mistakes are digital: photos, cloud notes, password managers synced to compromised accounts, or typing the words into a website claiming to verify them. Splitting a single phrase in half is weaker than it looks, because each half drastically reduces the attacker's search. No legitimate support team ever asks for your recovery words.