Cold storage refers to storing bitcoin private keys in a way that keeps them offline.
Because the keys are not connected to the internet, cold storage is generally considered more secure than online (“hot”) storage, especially for long-term holdings.
Cold storage can include:
- hardware wallets,
- paper backups,
- devices kept permanently offline.
The trade-off is convenience: accessing funds stored in cold storage typically involves more steps than using an online wallet or exchange - temporarily connecting your wallet to your computer to sign a transaction, for example.