Synthetic aperture radar is a type of radar which is used on aircraft and space-based systems like probes and satellites. The purpose of synthetic aperture systems is to scan the landscape or target area of interest over which it travels.
Inverse Synthetic Aperture Radar operates under the same basic principle but with one key difference: ISAR uses the movement of the target itself to generate its reading, rather than the movement of the radar emitter. ISAR is used in military applications for identifying and targeting objects by their movement.