HP Tc4400 - Compaq Tablet PC Reference Manual page 92

Glossary
Trusted Platform Module (TPM) embedded security chip
(select models only)—Integrated security chip that can protect
highly sensitive user information from malicious attackers. It is
the root-of-trust in a given platform. The TPM provides
cryptographic algorithms and operations that meets the Trusted
Computing Group (TCG) specifications.
USB token—Security device that stores identifying information
about a user. Like a smart card or biometric reader, it is used to
authenticate the owner to a computer.
Virtual token—Security feature that works very much like a
smart card and reader. The token is saved either on the computer
hard drive or in the Windows registry. When you log on with a
virtual token, you are asked for a user PIN to complete the
authentication.
Windows user account—Profile for an individual authorized
to log on to a network or to an individual computer.
Glossary–4 Reference Guide