"A hardware wallet is a special type of bitcoin wallet which stores the user's private keys in a secure hardware device. They have major advantages over standard software wallets:
A. Private keys are often stored in a protected area of a microcontroller, and cannot be transferred out of the device in plaintext
B. Immune to computer viruses that steal from software wallets
can be used securely and interactively, private keys never need to touch potentially-vulnerable software
C. Much of the time, the software is open source, allowing a user to validate the entire operation of the device."