Combat boots are military boots designed to be worn by soldiers during combat or combat training, as opposed to during parades and other ceremonial duties. Modern army boots are designed to provide a combination of grip, ankle stability, and foot protection suitable for a rugged environment. They are traditionally made of hardened and sometimes waterproofed leather. Today, many combat boots incorporate technologies originating in civilian hiking boots, such as Gore-Tex nylon side panels, which improve ventilation and comfort. They are also often specialized for certain climates and conditions, such as jungle boots, desert boots, and cold weather boots as well as specific uses, such as tanker boots and jump boots. The first soldiers known to have been issued boots were the foot soldiers of the Roman Empire.Roman soldiers wore hobnail boots, called caligae. By the late 1st century the army began to transition into an enclosed boot called calcei. They offered more protection and warmth than the caligae. They quickly became a staple in both Roman military and civilian dress.