A backpack (also called rucksack, knapsack, packsack, pack) is, in its simplest form, a cloth sack carried on one's back and secured with two straps that go over the shoulders, but there can be exceptions. Lightweight types of backpacks are sometimes worn on only one shoulder strap.
Backpacks are often preferred to handbags for carrying heavy loads or carrying any sort of equipment, because of the limited capacity to carry heavy weights for long periods of time in the hands. Large backpacks, used to carry loads over 10 kg (22 lbs), usually offload the largest part (up to about 90%) of their weight onto padded hip belts, leaving the shoulder straps mainly for stabilising the load. This improves the potential to carry heavy loads, as the hips are stronger than the shoulders, and also increases agility and balance, since the load rides nearer the wearer's own centre of mass.
In ancient times, the backpack was used as a means to carry the hunter's larger game and other types of prey as a way of easier transport. In the cases of larger hunts, the hunters would dismember their prey and distribute the pieces of the animal around, each one packing the meat into many wrappings and then into bags which they placed on to their backs. The bag itself was made up of different animal hide and skin (depending on what sorts of animals were in the area) and sewn together by the intestines of said animals, which were woven together tightly to make a sturdy thread-like material.
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The word backpack was coined in the United States in the 1910s. moneybag and packsack were used before; they now occur mainly as regionalisms. The word rucksack is a German loanword mainly used in the UK and in the US Army: in German 'der Rücken' means 'the back' (the part of the body), and Sack for bag. The name Rucksack is cognate with Danish Rygsæk, Norwegian Ryggsekk, Dutch Rugzak, Afrikaans Rugsak and Swedish Ryggsäck. Alternative names include Haversack, and in German language called Kraxe (in 19th century the term kraxeln was used for climbing).
Backpacks can often simply be referred to as "packs", especially in outdoors contexts; though sometimes ambiguous compared to other bags such as saddlebags and duffel bags, context is generally sufficient for identification.
A backpack fitted with pocket(s) that are suspended on the wearer's front side (chest) and loaded in such a way that the load in the front and the load in the back are about equal is called a bodypack. The majority of the load on a bodypack is carried by the hips.
The ideal load carrying system should not disturb the wearer's natural posture, balance and movement of the body. The load must be dispersed onto the skeletal structure in a balanced way, and should not produce forces on the body forward, aft, right, or left.
Backpacks in general fall into one of four categories: frameless, external frame, internal frame, and bodypack. A pack frame, when present, serves to support the pack and distribute the weight of its contents across the body more appropriately, by transferring much of the weight to the hips and legs. Most of the weight is therefore taken off the shoulders, reducing the chance of injury from shoulder strap pressure (many backpacks equipped solely with shoulder straps can affect the posture of a person carrying more than 14 kg (30 lbs)), as well as being less restrictive of the upper body range of motion. Most backpacks are capable of being closed with either a buckle mechanism, a zipper, or a dry-bag type closure though a few models use a drawstring fitted with a cord lock for the main compartment.
The simplest backpack design is a bag attached to a set of shoulder straps. Such packs are used for general transportation of goods, and have variable capacity. The simplest designs consist of one main pocket. This may be combined with webbing or cordage straps, while more sophisticated models add extra pockets, waist straps, chest straps, padded shoulder straps, padded backs, and sometimes reflective materials for added safety at night. These packs are generally produced inexpensively.
Some outdoor packs, particularly those sold for day hikes, ultralight backpacking and mountaineering are sometimes frameless as well.
The safety of some of the designs of these backpacks have been criticized by the UK NHS, many bag designs being deemed "unsafe" for children.
External frame packs were designed carry heavy loads (>20 kg or 40 lb), giving the wearer more support and protection and better weight distribution than a simple, frameless strapped bag. Wooden pack frames were used for centuries around the world. Ötzi the Iceman may have used one in Copper Age Alpine Italy [1][2], though some archaeologists believe the frame found with the body was part of a snowshoe. Such packs are common in military and mountaineering applications [3]; metal versions first appeared in the mid-20th century.
The frame of an external frame pack is typically made from aluminum, other lightweight metal alloy, and recently reinforced synthetic polymers or plastic and is equipped with a system of straps and tautly-stretched netting which prevents contact between the metal frame and user's back. In addition to comfort, this "stand-off" provides the additional benefit of creating air circulation between the frame and the wearer's back. For this reason, external frame packs are generally considered to be a "cooler load" than internal frame designs. External frame packs have a fabric "sack" portion which is usually smaller than that of internal frame packs, but have exposed frame portions above and below the sack to accommodate attachment of larger items. In addition, the sack can often be removed entirely, permitting the user to customize the configuration of his load, or to transport a non-conventional load such as a quartered game animal. Military packs are often external frame designs due to their ability to carry loads of different shapes, sizes and weights.
The internal frame backpack is a recent innovation, invented in 1967 by Greg Lowe, who went on to found Lowe Alpine and Lowepro, companies specializing in backpacks and other forms of carrying bags for various equipment.[4] An internal-frame pack has a large fabric section around an internal frame composed of strips of either aluminum, titanium or plastic, sometimes with additional metal stays to reinforce the frame. A complex series of straps works with the frame to distribute the weight and hold it in place. The internal frame permits the pack to fit closely to the wearer's back and minimizes shifting of the load, which is desirable when participating in activities that involve upper-body movement such as scrambling over rocky surfaces and skiing. However, the tight fit reduces ventilation, so these type of packs tend to be more sweaty than external frame packs. The internal construction also allows for a large storage compartment; a few lash points (including webbing loops and straps for sleeping bags and other large items) may be present, but as the frame is completely integrated, it is difficult to securely lash larger and heavier items which do not fit inside the compartment to the outside of the pack. Internal frame packs originally suffered from smaller load capacity and less comfortable fit during steady walking, but newer models have improved greatly in these respects. In addition, because of their snug fit, the improved internal frame models have largely replaced external frame backpacks for many activities.
In many countries, backpacks are heavily identified with students, and are a primary means of transporting educational materials to and from school.[5] In this context they are sometimes known as bookbags or schoolbags. The purchase of a suitably fashionable, attractive, and useful backpack is a crucial back-to-school ritual for many students.[6]
Typical school backpacks generally lack the rigid frame of an outdoor-style backpack and include only a few pockets in addition to the main storage compartment. While traditionally very simple in design, school backpacks are often made with padded shoulder straps and backs as well as additional reinforcement to hold large numbers of heavy textbooks, as well as safety features such as reflective panels to make the wearer of the pack more visible at night. Padded waist straps may also be provided to distribute weight across the body.
Backpacks are sometimes worn as fashion accessories, in which they perform the same function as a purse.[6] Some such backpacks designed specifically for women are no larger than a typical purse, and are generally associated with younger women.
Some backpacks are specifically designed to carry certain items. Common examples include backpacks for small valuable items such as laptops and cameras (see photo);[6] backpacks designed to hold laptop computers in particular generally have a padded compartment to hold the computer and medium sized pockets and flaps to accommodate accessories such as charger cables and cordless/corded mice. These are especially common in college and university settings. In order to supply these devices with electricity, a few high-end backpacks are equipped with solar panels.[7]
There are also single-strap packs that are essentially a hybrid between a backpack and a messenger bag.
Inexpensive, very simple packs that combine the drawstring and straps into a single piece of cloth or webbing are occasionally sold for use at sporting events and the like. Some high-end retailers (notably Apple Stores) use a similar design for their shopping bags as well.
Rolling backpacks are backpacks with wheels on the bottom and an extending handle. Because of their design, rolling backpacks reduce the strain on the user, though the shoulder straps may be used to carry the pack for short distances when the terrain is not suitable for wheels. Rolling backpacks are most commonly used while traveling by airplane or train.
Backpacks are a standard part of the load-bearing equipment of soldiers, especially infantry, in most countries, and military-style packs are regularly available to civilians in military surplus stores. Well-known examples include the United States ALICE field pack and the British Army PLCE rucksack attachment, both of which are widely available to civilian markets both as actual military surplus (new or used) and as replicas. Such packs are often, though not always (e.g. the USMC's ILBE pack), external-frame packs, with the pack itself lashed or pinned to a metal or plastic carrying frame. For units that are entering combat situations, packs may be loaded heavily and can weigh in excess of 100 lbs. Each soldier may carry extra weapons, ammunition, rations, medical supplies, tents or other shelter material, and extra clothing.
Many police tactical units, as well as players of military-style combat games such as paintball and airsoft, use military-style backpacks and webbing for storing gear and ammunition. There is also a small but thriving industry devoted to creating historical reproductions of military gear; such companies generally produce period-appropriate uniforms and other gear in addition to backpacks.
Some more recent military/tactical designs, especially the MOLLE and ILBE packs used by the United States armed forces, are covered with webbing loop attachment points for increased carrying capacity.
Backpacks are sometimes used as luggage, particularly as carry-on bags for airplane travel.
Backpacks form an essential part of the gear of the outdoor trekker and the urban backpacker, allowing more mobility and compactness than would be available to someone carrying most of their gear and clothing in a suitcase.
In addition to their use in outdoors pursuits, backpacks are sometimes used in other sports as well. Hydration packs, sometimes used by athletes and military personnel, carry water (in either a bladder or a rigid bottle) and have a tube connected to them from which the wearer can drink without removing the pack; this feature is also included in some more general-purpose hiking backpacks. Backpacks that carry skateboards have also become more popular in the youth culture.
One common special type of backpack (sometimes referred to as a "technical pack" or "frame pack") is designed for backpacking and other outdoors activities. These type of packs are more complex than most other backpacks. Compared to backpacks used for more day-to-day purposes such as schoolbooks, such packs are designed to carry substantially heavier loads, and as a result most such packs attach not only at the shoulders but at the hips, using a padded hip belt to evenly distribute the weight of the pack to the legs and back for better balance and comfort (this is a must for long hikes and extensive trips through trails.) The often heavily padded and sometimes semi-rigid shoulder straps are mainly for balancing the weight. They usually (except for those used in ultralight backpacking) have a metal or plastic frame to support and distribute the weight of the pack. Larger packs of this type tend to have a subdivided main compartment. These trekking packs often have several pockets on the outside; they may also have lash points on the exterior (either directly attached to the frame or webbing loops), so that bulky items may be strapped on, although depending on the pack design and type of trek most backpackers will try to stuff everything into the pack. Multiday packs typically have a content between 60 and 100 litres (and are about 3 ft /1 metre tall). Smaller packs with similar features are available for shorter trips.
The most common materials for such packs are canvas and nylon,(polyester), either ripstop fabric for lightweight packs or heavier fabric such as cordura for more typical usage. Most such packs are purpose-designed for the outdoors market; however, it is not uncommon for military surplus packing gear to be sold to outdoorspeople as well for the same purpose. The cheaper versions of the outdoor packs are often favoured by city trekkers; as they have a large volume and still carry relatively easily.
Outdoors packs, in addition to the distinction between external-frame and internal-frame, can be further subdivided based on the duration of trip a pack might be expected to be used on; daypacks hold supplies for a single day's hiking (size about 20-30 litres), while "weekender" bags can hold two to three day's worth of gear and supplies (sizes about 40-50 litres). Larger packs generally have no specific names but are designed to distribute the weight of increased numbers of gear and supplies for longer-duration trips (60-100 litres); such packs often include complex ergonomic support features to simplify the carrying of large amounts of weight. A third type with little or no frame at all, similar to the bookbags used by students and made of light fabric (often nylon ripstop, as mentioned above), is used in ultralight backpacking to eliminate the weight of the frame and heavy fabric used in more typical outdoors packs. Despite (or perhaps because of) their lesser weight, such packs are seldom less expensive than more typical, regular-weight packs.
In addition, outdoors packs are designed for specific purposes such as kayaking/canoeing, rock climbing, mountaineering, cross country skiing, and other such activities. Hydration packs are small backpacks containing a bladder-like plastic sac to hold up to three litres of water or any other beverage for hands-free drinking; they are sometimes known as camelbacks, from the CamelBak company, the best-known manufacturer of the packs. Packs used in competitive strategic sports such as paintball and airsoft are often based on or actually are military gear.
| Frameless | Internal frame | External frame |
|---|---|---|
| Non-rigid bag strapped to shoulders | Semi-rigid frame in the inside of the pack | Large rigid (metal, plastic, or wood) frame to which the pack is secured |
| Light, inexpensive, widely available | Tight fit, less bouncing | Heavier, good ventilation |
| Only suitable for light loads (less than about 5 kg) | Roomy internal storage, with occasional lash points for external items | Large capacity for bulky strap-on items |
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