Although food may be among the things we tend to focus on the most during a camping trip, it is not of primary importance for survival. Of the three basic things the human body needs on a regular basis---air, water and food---food is listed last for a reason. On average, a healthy human adult can go about three weeks without food and still be healthy and functioning. So in a survival situation, try not to think with your stomach. (Air is our most immediate need, but except in extreme and perhaps rare circumstances air is something we can assume will be available.)
Water is a different matter. The rule of three states that the average healthy human adult can go only three days without water. So, next to air water is obviously a big priority. Not just any water will do, either; it must be potable water. Water laced with pathogens that are going to make us ill---possibly causing diarrhea which is very dehydrating---can be as bad as no water at all. You must make sure that your water is clear of contaminants to begin with or that it can be made that way by treatment. There are various forms of treatment, including boiling, treating with iodine and filtration. Be equipped and prepared to use these methods if necessary.
Shelter is another basic human need. Depending upon the elements, shelter can be more or less of a priority at any given time. When it's not precipitating and the temperature range is within comfortable limits, shelter is less important than during weather extremes. Shelter means not only shelter from rain but potentially from wind, sun, snow, sleet, hail and lightening---virtually anything that nature and the atmosphere can throw at us. For camping survival, learn and practice in advance how to make a shelter, like a lean-to, using naturally available materials.
Clothing is an extension of shelter. It's like portable shelter that we walk around in. One well-known rule of survival is that cotton clothing is your enemy and wool and synthetics are your friends. Cotton, when wet, wicks away moisture and has virtually no insulating properties. Natural wool or synthetic materials, on the other hand, can provide life-saving insulation even when wet.
As with many endeavors, the factors involved with camping survival are interrelated. Hypothermia is a serious and potentially deadly condition in which the body's core temperature drops to dangerous levels. This can come about as a result of exposure to cold, wet conditions. Preventing exposure to these conditions can be accomplished by having adequate shelter and clothing. And the opposite extreme, heat exhaustion or heatstroke, can likewise be prevented with proper clothing and shelter and adequate hydration.
Always keep in mind the rule of threes. There are variations, but essentially the rule states that we can go for three minutes without air, three days without water and three weeks without food. Some versions of the rule state that we can go for three hours without shelter. Remember that the weather can change quickly and shelter can quickly become a necessity.
