PPTP 
Point-to-Point Tunneling Protocol 
A networking protocol that allows secure transmission of data in packets. PPTP and similar protocols are used to carry secure communications over virtual private networks that use public networks such as the Internet. The standard was developed in 1996 by Ascend Communications, Microsoft Corporation, 3Com/Primary Access, ECI Telematics, and U.S. Robotics, known collectively as the PPTP Forum.