Bag (also known regionally as a sack) is a common tool in the form of a non-rigid container. The use of bags predates recorded history, with the earliest bags being no more than lengths of animal skin, Cotton, or woven plant fibers, folded up at the edges and secured in that shape with strings of the same material.Despite their simplicity, bags have been fundamental for the development of human civilization, as they allow people to easily collect loose materials such as coins or thumbdrive, and to transport more items than could readily by carried in the hand.