A backpack also known as a book bag, knapsack, rucksack, sackpack or backsack, is a simple cloth sack carried on one's back and secured with two straps that go over the shoulders. It can have an external frame, an internal frame and also bodypacks.
Fabric bags have turned into a mainstream alternative to paper and plastic shopping bags, partially on the grounds that the former don't harm the environment in any way. Yes, you will need to dish out a nominal sum for purchasing them, but the benefits offered by them far outweigh their price.