AXAF is NASAs Great Observatory for X-ray astronomy, planned for launch in 1996 and operation through 2011. It contains a 1.2m diameter telescope assembly with 6 grazing incidence mirrors giving 0.5 arc second angular resolution and reasonable efficiency at energies up to 9 keV. The telescope can be aligned with any one of four complementary instruments at the focal plane: two imagers, the High Resolution Camera and the CCD Imaging Spectrometer, and two spectrometers, the X-ray Spectrometer/Calorimeter and the Bragg Crystal Spectrometer. Either of two transmission grating assemblies, one low energy and one high energy, can be used to disperse an X-ray spectrum across one of the imaging detectors. Compared to Einstein, AXAF and its instruments have ten times better angular resolution, 100 times better sensitivity for point source detection, and 1000 times better sensitivity for spectroscopy. This makes it a powerful observatory for performing detailed studies of the X-ray emission from every type of astrophysical object, from nearby stars to nearby galaxies to the most distant quasars.