Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Precision Time Protocol (PTP) is a high-precision time protocol for synchronization used in measurement and control systems residing on a local area network. Accuracy in the sub-microsecond range may be achieved with low-cost implementations. PTP was originally defined in the IEEE 1588-2002 standard, officially entitled "Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems". In 2008 a revised standard, IEEE 1588-2008 was released. This new version, also known as PTP Version 2, improves accuracy, precision and robustness but is not backwards compatible with the original 2002 version. "IEEE 1588 is designed to fill a niche not well served by either of the two dominant protocols, NTP and GPS. IEEE 1588 is designed for local systems requiring very high accuracies beyond those attainable using NTP. It is also designed for applications that cannot bear the cost of a GPS receiver at each node, or for which GPS signals are inaccessible."