A hardware wallet is a physical device that stores cryptocurrency private keys in a separate, hardened environment and signs transactions without exposing those keys to a general-purpose computer. The device usually keeps the seed offline, then shows transaction details on its own screen so the user can confirm what will be signed.
This matters because the security of self-custody depends on the integrity of the signer, not just on keeping keys off the internet. Hardware wallets reduce malware risk, phishing damage, and key theft, but they do not remove all risk. Attacks can target compromised firmware, fake device updates, seed-phrase theft, or misleading transaction prompts. Defenders rely on verified firmware, physical-device checks, secure backups, and careful on-device confirmation to ensure the wallet signs only the intended transaction.