Joint Direct Attack Munition
The Joint Direct Attack Munition (JDAM) is a guidance kit that converts unguided bombs, or "dumb bombs", into all-weather precision-guided munitions (PGMs). JDAM-equipped bombs are guided by an integrated inertial guidance system coupled to a Global Positioning System (GPS) receiver, giving them a published range of up to 15 nautical miles (28 km).
Source: Wikipedia — Joint Direct Attack Munition (CC BY-SA 4.0)