Survival skills are techniques that a person may use 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 which include water, food, and shelter. The 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 often associated with the need to survive in a disaster situation. Survival skills are often basic ideas and abilities that ancients invented and used themselves for thousands of years. Outdoor activities such as hiking, backpacking, horseback riding, fishing, and hunting all require basic wilderness survival skills, especially in handling emergency situations. Bush-craft and primitive living are most often self-implemented, but require many of the same skills.