A punching bag is a sturdy bag designed to be repeatedly punched, for use in physical exercise or stress relief in order to improve one of three areas: physical strength, aerobic fitness, or punching technique.
In martial arts and combat sports such as Karate, Taekwondo, and Muay Thai; heavy bags, standing bags, and similar apparatuses have been adapted for practicing kicking and other striking maneuvers in addition to developing punching technique.
Speed bags are small, air-filled bags anchored at the top to a rebound platform parallel to the ground. Speed bags help a fighter learn to keep his hands up, improve hand-eye coordination and learn to shift weight between feet when punching.
Double-end bags or Focus bags are light, round bags, often anchored to floor and ceiling with elastic or semi-elastic materials. These types of bags are used to practice mobility and accuracy on a moving target.
Maize bags are not punched with great force but are used in boxing training to improve the athlete's head motion and ability to evade an opponent's punch, their name deriving from the fact that traditionally they are filled with maize.
A heavy bag is a larger, cylindrical bag, usually suspended by chains or ropes for practicing powerful body punches.
Pedestal bags or tower bags are heavy bags mounted on a weighted pedestal rather than being hung from above. Other variations on the standard heavy bag include horizontal suspension from both ends to practice uppercut punches and non-cylindrical shapes.
Body-shaped training aids such as the modern "body opponent bag" and the fabled "slam man" are made primarily of synthetic materials, and punching bags are sometimes mounted on a weighted pedestal rather than hanging from above. These are not punching bags in the strict sense, but modern versions of apparatus such as the wooden man apparatus of Chinese Wing Chun, the medieval quintain and target dummies used in modern bayonet training. Large inflatable balloons with weighted bases are another kind of punching bag, often painted with a picture and sold as a children's toy.