The pack consists of a baggage that can be worn on the back by two bands that go around her. The person who uses a backpack is usually called backpacking. They usually prefer to use backpacks instead of purses, for transporting heavy loads over long periods of time, because the shoulders bear the weight better hands. The larger bags unloaded most of the weight belt around the hips, leaving the bands that pass through the shoulder only to stabilize the load. This allows for heavy loads because the hips are even stronger than the shoulders and improve agility and balance because the burden lies near the center of mass of the body. This also allows downloading the backbone of burden that may be damaged. The military backpack has its origins in prehistory, when the man needed to transport their belongings in the back. Over time this article has evolved with the need to carry more and heavier objects. Wars have been major drivers of its development, both in design and materials. There are various models of backpacks, as the specific goal: climbing, hiking, travel, military, and carriers, to name a few. There are also calls hydration backpacks, which are manufactured specifically to carry inside a pond. These in turn have a hose that goes over the shoulder, so, who carries the military backpack can easily hydrated. According Coromines comes military backpack "errand boy" for being a garment characteristics. It comes from the Basque mutil or motile (short motxil) "Boy," "servant". In turn comes from the Latin mutilus, "maimed," "mop" the habit of fleecing the Raptors. We are facing an upcoming Basque etymon: mutil or motile, taken from a remote etymon mutilus. . military backpack means, according to the dictionary Vox bag or cloth bag are subject to strong back hunters and hikers. We observe a sense contiguity (metonymy), and that the "errand boy" happens to designate "knapsack", producing an association of pars pro toto, the bag passes the term to designate a person who runs errands to designate garment characteristics. . From 40 to 65 liters: Its most common use is for activities in which at least are going to spend a night out, as it is necessary to take the sack, bivy, stove, etc. . Sanity, a derivative of the polyamide, the material used today for the construction of rucksacks as it is endowed with an excellent weight and resistance to abrasion and tearing. The recommended thicknesses ranging from 500 to 1000 denier. Through a finish coating, resin or induced polyurethane waterproofing is achieved backpacks, but the seams will always be the preferred routes of water to make inroads in clothing, bag and other things that we carry inside. Some backpacks superlight medium and high capacity use fabrics such as Kevlar, fiberglass, high resistance to abrasion, for its construction. Currently, the backpacks have replaced the seats in the transport of books by children. Backpacks are used to carry both school textbooks and notebooks like the rest of school supplies: boxes, pens, markers, etc. . They also serve to carry lunch and other items such as coats, gym clothes, sports, etc. . The backpacks are considered a better option portfolios as the weight more evenly distributed in the back of the child. We recommend having two symmetrical adjustable straps depending on the child's height. Both strips as part of the military backpack that rests on the back should be padded to avoid damaging the wearer's body. The military backpack should always be a few inches above the waist of the child. Also, you should put on and take avoiding awkward postures that may cause muscle injuries. The problems currently faced by children are caused by poor placement of the bags, and by the excessive weight requires schools to carry every day. . . . .