A boxing bag, also known as a punching bag, is an essential piece of equipment used in boxing and martial arts training. It's typically a heavy cylindrical bag filled with materials like sand or fabric, enclosed in a durable outer shell made of leather or synthetic materials. Boxing bags come in various sizes and weights, catering to different training purposes such as speed bags for quick punches or heavy bags for strength and endurance training. They provide a target for practicing punches, kicks, and combinations, helping athletes improve technique, power, and stamina.