A survival kit contains basic tools and supplies to help a person in an emergency situation. It provides shelter, warmth, first aid, food and water, signaling, and navigation. Civilian workers in remote areas may also carry survival kits, as do those in disaster-prone areas. Proper hydration is important for survival, with a person needing 4-6 liters of water daily. Shelters can range from natural to completely man-made structures. Navigation techniques include using the sun, stars, maps, and natural landmarks. Mental toughness and a will to live are also critical for survival.