A backpack is a bag carried on one's back, typically supported by two shoulder straps. It's designed for carrying various items, from everyday essentials and school supplies to hiking gear and travel necessities. Backpacks come in a wide range of sizes, materials, and styles, often featuring multiple compartments, zippers, and sometimes external pockets or attachment points for water bottles or other equipment. They are a practical and popular choice for hands-free carrying, distributing weight across the shoulders and back for comfort, especially over longer periods or distances.