(1) See peer-to-peer.

(2) (Picture Transfer Protocol) An ISO standard for transferring photos from a digital camera to a computer or photo printer. PTP is supported in all new digital cameras, photo printers and photo applications as well as Windows, Mac and Linux. PTP allows vendors to add an extension number to PTP packets in order to identify and support proprietary functions in their models.

USB and the Network
PTP is the "still image capture" device class standard for USB, which is the typical transport mechanism between camera and computer. However, PTP can be extended across a TCP/IP network with PTP-IP. Introduced in 2005, PTP-IP maps PTP packets onto TCP, enabling camera images to be transferred wireless via Wi-Fi to the computer. See MTP.

(3) (Precision Time Protocol) An IEEE protocol used to provide exact time within local networks. PTP can be used in conjunction with the network time protocol (see NTP).