Key Fob

A key fob usually has a small screen so it can display whatever security code it was meant to contain. It is used as part of a multifactor identification process, which is required for high-security systems. More common security measures are a username and a PIN/password combination, while others only require a certain key or smart card. But two-factor identification requires both, meaning that the person must supply the personal identification credentials plus the associated security device, in this case the key fob.