In terms of exchanges, a hot wallet is a wallet that is online and is used for storing small amounts of coins that are needed for day-to-day transactions, such as withdrawals and deposits. They are more vulnerable to hacking and exploit attempts, and therefore they are not recommended for storing large amounts. On the other hand, a cold wallet is a cryptocurrency wallet that is not connected to the internet and is used for storing large amounts of coins that are not needed for immediate use. Cold wallets can also have additional protections, such as multisig, so that there are multiple keys needed to access the funds. A hardware wallet is a typical type of cold wallet that stores the user's private keys on a dedicated device, but there are other types as well.