A hardware wallet is a type of cryptocurrency wallet that stores a user's private keys in a secure hardware device, rather than on a computer or mobile device. Private keys are the codes that allow users to access and control their cryptocurrencies.

Hardware wallets are considered to be one of the most secure options for storing cryptocurrencies, as they are not connected to the internet and are therefore less vulnerable to hacking attempts. They also typically require a physical confirmation to initiate transactions, adding an extra layer of security.

Hardware wallets come in various forms, including USB drives and smart cards. Some popular examples of hardware wallets include Trezor, Ledger, and KeepKey.

While hardware wallets offer a high level of security, they do come with some disadvantages. They can be relatively expensive compared to other wallet options, and users must take extra precautions not to lose or damage the physical device. Nonetheless, for those looking to store larger amounts of cryptocurrency over the long term, a hardware wallet can provide peace of mind and security.