Backpack (also known as schoolbag, toolkit, backpack, backpack, knapsack or sack knapsack), the simplest form is a cloth bag, carrying a cloth bag, and fixed with two straps tied on the shoulder, but there are many options for this basic design. Light backpacks are sometimes worn only on one shoulder strap.

Backpacks are usually used by hikers and students, because they have limited ability to bear heavy objects in their hands for a long time, so handbags are usually preferred when carrying heavy objects or any type of equipment.

Large backpacks are usually used to carry more than 10 kilograms (22 pounds), while smaller sports backpacks (such as running, cycling, hiking and water replenishing) usually unload a part of the maximum weight (up to about 90%) onto the padded hips. Waistband, left shoulder belt is mainly used to stabilize the load. Because the hips are stronger than the shoulders, it increases the possibility of carrying heavy loads, and because the loads are close to the wearer's own center of gravity, it also improves agility and balance.

In ancient times, backpacks were used as tools to carry large prey and other types of prey of hunters, and as a way to transport other materials more easily. They are also easy to carry and made of cloth. In the case of large-scale hunting, the hunter will disperse the prey and scatter the fragments of the animals, each of which will pack the meat into many packages, then put it into a bag, and then put it on the back. The bag itself is composed of animal skin and skin, and is sewn together by animal intestines, and then they are tightly woven together to make a solid linear material.