Survival skills are techniques used in order to sustain life in any type of natural environment or built environment. These techniques are meant to provide basic necessities for human life, including water, food, and shelter. Survival skills also support proper knowledge and interactions with animals and plants to promote the sustaining of life over a period of time. Survival skills are basic ideas and abilities that ancient peoples invented and passed down for thousands of years. Today, survival skills are often associated with surviving in a disaster situation. Outdoor activities such as hiking, backpacking, horseback riding, fishing, and hunting all require basic wilderness survival skills, especially to handle emergency situations. Individuals who practice survival skills as a type of outdoor recreation or hobby may describe themselves as survivalists. Survival skills are often used by people living off-grid lifestyles such as homesteaders. Bushcraft and primitive living are most often self-implemented but require many of the same skills. There are also many instances of survival skills being utilized by criminals, such as fugitives, draft dodgers, poachers, serial killers, illegal immigrants, escaped prisoners, organized criminals and terrorists, who avoid capture by authorities by hiding in wilderness areas. Additionally, both park rangers and conservation officers are taught survival skills to help them find missing persons, and in case they themselves become stranded while investigating wilderness crimes. The United States Armed Forces has a training program called SERE, in which military personnel, Department of Defense civilians, intelligence personnel, and private military contractors are taught survival skills and techniques for evading capture and escaping from captivity, in the event that they need to survive and hideout in wilderness areas while avoiding capture by enemy combatants. First aid First aid (wilderness first aid in particular) can help a person survive and function with injuries and illnesses that would otherwise kill or compromise them. Common and dangerous injuries include: Bites from snakes, spiders and other wild animals Bone fractures Burns Drowsiness Headache Heart attack Hemorrhage Hypothermia and hyperthermia Infection from food, animal contact, or drinking non-potable water Poisoning from poisonous plants or fungi Sprains, particularly of the ankle Vomiting Wounds, which may become infected The person may need to apply the contents of a first aid kit or, if possessing the required knowledge, naturally occurring medicinal plants, immobilize injured limbs, or even transport incapacitated comrades. Shelter Many people who are forced into survival situations often have an elevated