The backpack, also known as knapsack or schoolbag, rucksack and rucksac and pack, sackpack and booksack, bookbag, backsack, is a simple frameless fabric bag that can be carried on the back. It has two straps that go across the shoulders and is secured with two straps. There are also bodypacks.

Backpacks are used frequently by hikers as well as students. They are more suitable than handbags to transport heavy loads or carry any equipment.

Large backpacks can be used to transport loads of over 10 kg (22 lb) as well as smaller backpacks for sports (e.g. Running, cycling, hiking, and hydration often offload large backpacks (up to 10 kilograms) onto padded hip belts. The shoulder straps are used primarily for stability. Because the load is closer to the wearer's center of weight, it makes it easier to transport heavy loads.