What is a cold wallet

A cold wallet is a device or piece of paper that stores crypto private keys completely offline, away from any internet connection, so hackers can't reach them remotely. This matters because most crypto theft happens through online exploits, and keeping keys offline removes that entire attack surface for savings you don't touch daily. A common example is a Ledger or Trezor hardware wallet costing $60-$150, where you approve transactions by pressing a physical button on the device itself.

The follow-up question people usually have: how do you actually use it if it's offline? You plug the device in only when signing a transaction, then disconnect it. The signed transaction broadcasts through your regular internet-connected computer, but the private key itself never touches that computer or the web.