An oxygen cylinder is a high-pressure container that stores oxygen gas for various uses, including medical, industrial, and recreational applications. These cylinders are typically made of steel or aluminum and come in different sizes, allowing for portability and ease of use. In medical settings, oxygen cylinders provide supplemental oxygen to patients with respiratory issues, ensuring they receive the necessary amount of oxygen for their health. In industrial applications, they are used for welding and cutting metals, while in recreational activities like scuba diving, they supply breathable air underwater.