Created by the the FIDO (Fast IDentity Online) Alliance, Universal 2nd Factor (U2F) is a strong industry standard for two-factor authentication.
Once enrolled with Duo, users can quickly tap a physical USB device plugged into their device in order to log into their accounts securely. Known as a U2F authenticator, the device protects private keys with a tamper-proof component known as a secure element (SE).
There are no special drivers required; all you need is a supported web browser, operating system and a U2F device, such as Yubikey Neo provided by Yubico.
U2F is one of many two-factor authentication methods that Duo provides to support your diverse user base.