risk of danger because of direct exposure to the elements. Many people in survival situations die of hypothermia or hyperthermia, or animal attacks. An effective shelter can range from a natural shelter, such as a cave, overhanging rock outcrop, or a fallen-down tree, to an intermediate form of man-made shelter such as a debris hut, tree pit shelter, or a snow cave, to a completely man-made structure such as a tarp, tent, or a longhouse. It is noted that some common properties between these structures are: Location (away from hazards, such as cliffs; and nearby materials, like food sources) Insulation (from ground, rain, wind, air, or sun) Heat Source (either body heat or fire-heated) Personal or Group Shelter (having multiple individuals) Fire Fire is a tool that is helpful for meeting many survival needs. A campfire can be used to boil water, rendering it safe to drink, and to cook food. Fire also creates a sense of safety and protection, which can provide an overlooked psychological boost. When temperatures are low, fire can postpone or prevent the risk of hypothermia. In a wilderness survival situation, fire can provide a sense of home in addition to being an essential energy source. Fire may deter wild animals from interfering with an individual, though some wild animals may also be attracted to the light and heat of a fire. There are numerous methods for starting a fire in a survival situation. Fires are either started with a concentration of heat, as in the case of the solar spark lighter, or through a spark, as in the case of a flint striker. Fires will often be extinguished if either there is excessive wind, or if the fuel or environment is too wet. Lighting a fire without a lighter or matches, e.g. by using natural flint and metal with tinder, is a frequent subject of both books on survival and in survival courses, because it allows an individual to start a fire with few materials in the event of a disaster. There is an emphasis placed on practicing fire-making skills before venturing into the wilderness. Producing fire under adverse conditions has been made much easier by the introduction of tools such as the magnesium striker, solar spark lighter, and the fire piston. Water A human being can survive an average of three to five days without water. Since the human body is composed of an