The principal equipment needed to ski includes skis, ski boots, and bindings. Skis are essential for gliding down the slopes, while boots provide the necessary support and control. Bindings secure the boots to the skis, allowing for effective maneuverability and safety. Additional gear often includes ski poles, which assist with balance and propulsion. Proper attire, including warm clothing, goggles, and helmets, is also vital for safety and comfort. Each piece of equipment plays a key role in enhancing performance and enjoyment on the slopes.