The YubiKey is in essence a second authentication method based on a unique physical USB token which cannot be duplicated or recorded.
These provide a second level of authentication, whereby the user must enter the right login credentials and have the Yubikey to hand, in order to log in successfully. Yubikeys are assigned to individual users and cannot be transferred.
Yubikeys have several advantages over traditional smart cards. They don’t require additional card-readers or complex software to be installed. Any computer which can use a USB keyboard can use the YubiKey, regardless of the computer hardware, operating system or system drivers. Yubikeys are easy to operate, easy to transport, safe and secure. No transfer of non-security related data means the YubiKey will never be a vector for viruses, Trojans or other malware.