Joint Direct Attack Munition. A GPS-guided free-fall bomb available in the 500- / 1,000- / and 2,000-pound classes.

OPERATION IRAQI FREEDOM -- A weapons loader prepares a GBU-31 joint direct attack munition for a mission at a forward-deployed location.  Smart bombs like the JDAM have comprised 80 percent of the munitions used during this operation.  (U.S. Air Force photo by Staff Sgt. Jessica Kochman)