A general-purpose bomb is an air-dropped bomb intended as a compromise between blast damage, penetration, and fragmentation in explosive effect. It is a common weapon of fighter bomber and attack aircraft because it is useful for a variety of tactical applications and relatively cheap. Most modern air-dropped general-purpose bombs are designed to minimize drag for the carrier aircraft. The primary U.S. general-purpose bombs are the Mark 80 series.
General-purpose bombs are commonly used as the warheads for more sophisticated precision-guided munitions. Affixing various types of seeker and electrically controlled fins turns a basic gravity bomb into a laser-guided bomb, like the U.S. Paveway Series.
A gravity bomb is an aircraft-delivered bomb that does not contain a guidance system and hence, simply follows a ballistic trajectory. Then, with the dramatically increased use of precision guided munitions, a new term was needed to separate smart bombs from those that weren't. Dumb bomb was used for a time, then the term gravity bomb gained currency.
Precision-guided munitions (PGMs, smart munitions, smart bombs, guided bomb units or GBUs) are guided weapons intended to precisely hit a specific target, and to minimize damage to things other than the target. A guided bomb differs from a guided missile in that a bomb relies on the speed and height of the launch aircraft for propulsion, whilst a missile has an onboard engine.
The Joint Direct Attack Munition (JDAM) is a guidance kit that converts existing unguided gravity bombs, or dumb bombs, into all-weather smart munitions. JDAM equipped bombs are guided to their target by an integrated inertial guidance system coupled with a Global Positioning System (GPS) receiver for enhanced accuracy,
Laser guided bombs remain the most numerous precision guided munition, with roughly 25,000 in the current inventory. The development of laser guided weapons has dramatically improved the accuracy of weapon quidance and delivery. With the assistance of build-up guidance kits, general-purpose bombs are turned into laser-guided bombs.
There are three generations of Paveway laser-guided bomb technology, each successive generation representing a change or modification in the guidance mechanism. Paveway I was a series of laser guided bombs with fixed wings. Paveway II [with retractable wings] and Paveway III are the Air Force designations for 500- and 2,000-pound-class laser-guided bombs (LGBs). A guidance control unit is attached to the front of the bomb, and a wing assembly is attached on the rear. Both generations are compatible with current Army, Navy (Marine), and Air Force designators.