Design of the backpack

In general, backpacks fall into one of four categories: frameless, frameless, framed, framed, and fanny packs. When a pouch frame is present, by transferring most of the weight to the hips and legs, the pouch frame is used to support the pouch and distribute the weight of its contents more appropriately over the entire body. As a result, most of the weight is shifted to the shoulders, reducing the chance of injury from shoulder strap pressure (many strap-only backpacks may affect the posture of people over 14 kg (30 lbs)) and less restrictive upper body range of motion. Most backpacks can be closed with a buckle mechanism, zipper, or dry bag closure, although a few models use a wire lock with a main compartment.

A fanny pack is a backpack with one or more pockets that hang over the wearer's chest and are loaded in such a way that the front and rear loads are nearly equal. Most of the load in the fanny pack is carried by the hips. The ideal load system should not interfere with the wearer's natural posture, balance and maneuverability. The load must be evenly distributed over the bone structure and not create unbalanced forces on the body.