A composite cylinder is a pressure vessel constructed using advanced composite materials such as carbon fiber, glass fiber, or aramid fiber, usually reinforced with a resin matrix. Unlike traditional steel cylinders, composite cylinders are lighter in weight yet provide high strength and durability. They are designed to withstand extreme pressure while offering safety, efficiency, and ease of handling. Composite cylinders are widely used to store gases such as liquefied petroleum gas (LPG), compressed natural gas (CNG), hydrogen, oxygen, and other industrial or medical gases. They are increasingly replacing conventional steel cylinders in various industries ranging from energy and automotive to healthcare and aerospace due to their innovative design and material advantages.