//EDITOR NOTES:
Change this wikipedia guide to add more details and remove some. Its important to keep a person knowledgeable. Must add pictures to edible foods. Water could use pictures and a guide to use what is available on a person is helpful.

Survival priorities

In most survival situations, four priorities must be addressed before any other needs are met:

1. Finding or making shelter is the most important survival priority because it allows a person to stay protected from the elements, and thus hopefully warm and dry.
2. Humans can live for only about three days without water.
3. Fire helps to purify water, provide warmth, scare away dangerous animals, and signal to other people.
4. A human can survive for weeks without food, but hunger impairs judgment and clarity of mind, and makes one weak and susceptible to disease.

Shelter

A shelter will protect one from potentially disastrous weather, help prevent hypothermia, and allow restful sleep. It will also boost morale, as it will become a base or home. Therefore, in typical survival situations, a shelter should be built first. A shelter should provide a somewhat comfortable place to sleep. To this end, it should account for the following:

• Immovable rocks, animal nests, and other obstacles and hazards should be avoided.
• Dry watercourses may be flat, sandy, and comfortable to sleep on, but they will flood in a storm.
• Sunlight will provide warmth (which is not always welcome), and help one to wake up in the morning. However, sunny, open areas are vulnerable to wind.
• Heat transfer: an excessively large or well-ventilated shelter will not retain warmth well.

A simple shelter can be constructed using a lattice of branches propped up at an angle against the wind. Large leaves, such as ferns or fir branches, can then be added to create cover for rain and hail. Branches propped against a fallen tree make a simple and effective shelter, but animals such as ants and snakes may nest under the tree.

Water

Humans can live for several weeks without food, but only about three days without water. A typical person will lose 2-3 liters of water per day in ordinary conditions, but more in very hot or dry weather. A lack of water causes dehydration, resulting in lethargy, headaches, dizziness, confusion, and eventually death. Even mild dehydration impairs concentration, which is dangerous in a survival situation where clear thinking is essential. Dark yellow or brown urine indicates dehydration. Because of these risks, a safe supply of drinking water must be located as soon as a shelter is built (or even before, depending on conditions). In a survival situation, any water supply may be contaminated with pollutants or pathogens (see Potability of backcountry water). Although little can be done to remove molecular contaminants, particles and microorganisms can be removed and/or killed (see Portable water purification). Water can be gathered in numerous different ways. In areas of abundant moisture, water can be scooped out of a creek or pond. Rainwater (which is safe to drink) can be caught in makeshift containers. If these easy sources are not available, a bit more ingenuity will be necessary. Water can be collected from condensation traps or solar stills. Clothing can be used to collect dew from vegetation. Animal blood is not suitable for rehydration, as it may be diseased. In addition, because of the nutrients it contains, it requires energy to digest. Urine contains salt and other toxins, which also makes it unsuitable to drink, although it can be refined in a solar still. In extremely dry environments, it is necessary to take extra care to prevent water loss by:

• Breathing through the nose to prevent water vapour escaping through the mouth
• Not smoking
• Resting in the shade and avoiding strenuous labor during sunny, hot periods
• Not eating too much (the human body uses a lot of water to digest food - especially fats and proteins)

Fire

A fire is as important as a safe water supply, because of its many uses:

• Boiling water to kill pathogens (see above)
• Cooking food, including wild-caught fish and game (see below)
• Staying warm, particularly when wet
• Repelling dangerous animals
• Signaling to rescuers (bright at night, smoky by day)

See also: Campfire, Ignition device

Food

Food is not urgently needed in survival situations, since a human can survive for several weeks without it. However, much like dehydration, hunger can bring about many consequences long before it causes death, such as:

• Irritability and low morale
• Weakness
• Loss of mental clarity, such as confusion, disorientation, or poor judgment
• Weakened immune system
• Difficulty maintaining body temperature (see heat exhaustion and hypothermia)

It is actually rather easy to find food in the wild, provided one knows where to look. A basic knowledge of animal trapping, hunting, and fishing will provide meat. Equally important is a knowledge of edible plants, fungi, and lichens. One cannot always rely on the most abundant or most easily accessible type of food. To survive for long periods of time, one must maintain a balanced diet. In order to do this, one must consume a balanced variety of foods. Many survival books promote the "universal edibility test": allegedly, one can distinguish edible foods from toxic ones by tasting progressively larger portions over time. However, many experts (such as Ray Mears) deprecate this method, in main part because a very small amount of some "potential foods" can cause anything from gastric distress to illness or death.