World-wide, several detectors currently running or nearing completion are sensitive to a prompt core collapse supernova neutrino signal in the Galaxy. The SNEWS system will be able to provide a robust early warning of a supernova's occurrence to the astronomical community using a coincidence of neutrino signals around the world. This talk describes the nature of the neutrino signal, detection techniques and the motivation for a coincidence alert. It describes the implementation of SNEWS, its current status, and its future, which can include gravitational wave detectors.

7 pages, for the Proceedings of the 3rd Amaldi Conference on Gravitational Waves