The Stanford Linear Accelerator Center (SLAC) is a linear particle accelerator (linac) operated by Stanford University. SLAC is the longest linear accelerator in the world, accelerating electrons or positrons for two miles. The collision energy when the accelerated particles hit a fixed target is 50 GeV. Since the SLAC began operation in 1966, its results have led to Nobel Prizes for the discovery of the J/Psi particle, which provided evidence for the existence of the charm quark, the discovery of structure inside protons and neutrons indicating that they are made of quarks, and the discovery of the tau lepton. SLAC is now used in a wide variety of projects that range from astrophysics to biology, chemistry, and materials science.