Bitcoin glossary
Keys kept fully offline — the vault tier of bitcoin security.
Cold storage means private keys that never touch an internet-connected device: hardware wallets, air-gapped computers, or steel seed backups in a safe. “Hot” wallets on phones and exchanges are for spending; cold storage is for saving.
The pattern mirrors cash: a wallet in your pocket, a vault for the rest. Most bitcoin lost to hacks was hot; most bitcoin held for years is cold.