A rebreather is a type of breathing apparatus that recycles exhaled air. It removes carbon dioxide and adds oxygen, allowing the user to breathe the same air multiple times. This technology is commonly used in diving, military operations, and rescue missions, as it reduces the amount of gas needed and minimizes bubbles, making it less detectable underwater. Rebreathers come in various designs, including closed-circuit and semi-closed systems. They are often preferred by experienced divers for extended underwater exploration. Proper training and maintenance are essential for safe operation, as malfunctioning equipment can lead to serious risks, including hypoxia or hypercapnia.