Survival skills are techniques a person may utilize for an indefinite duration in order to survive a dangerous situation (also see bushcraft). Generally speaking, these techniques are meant to provide the basic necessities of human life: shelter, water, and food. They may prove useful in situations such as storm or earthquake, or in dangerous locations such as desert, mountains, and jungle. Every different situation or location presents a different range of dangers - (see hazards of outdoor activities). An environment may be dry, wet, hot, cold, high altitude, low altitude, desert, rural, urban, wilderness, subterranean, or an island. Techniques exist to fit most situations. Examples of survival skills include: