From Permanent Future Lab
The TREZOR is a hardware Bitcoin wallet. It is designed to protect your Bitcoins from viruses, hackers and thieves. Official website. The TREZOR is a USB device that protects your private key and make sure it never leaves the device.
This key is what allows the software to spend your Bitcoins safely.
Since June 2016 TREZOR offers a password manager that unlocks with TREZOR.