A backpack (also called rucksack, knapsack, packsack, pack, bookbag or Bergen)'s, 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. Light weight types of backpacks are sometimes worn on only one shoulder strap, or in the hand like an ordinary bag. Backpacks are often preferred to handbags for carrying heavy loads, because of the limited capacity to carry heavy weights for long periods of time in the hand… (More on Backpacks)