(1) For regular storage, hot and cold refers to their quick accessibility. Hot storage devices are disk drives and solid state drives (SSDs) plugged into a computer and typically contain data that are frequently accessed. Cold storage refers to magnetic tape cartridges and USB drives that hold data that are accessed infrequently. See
HSM and
hot backup.
(2) For crypto wallets, hot and cold refers to their Internet connection. Hot storage means the digital wallet that contains the private key is an app that can access the Internet. Cold storage means the key is in a wallet contained in a USB drive that is currently not plugged into a computer. See
crypto wallet.