A bag (also known as a sack) is a non-rigid or semi-rigid container, made of paper, cloth, plastic, leather, or some other flexible material.

A bag may or may not be disposable; however, even a disposable bag can often be devoted manifold times, not only for industrial but also for environmental reasons. Promotional Tote Bags On the other hand there may be logistic or hygienic reasons to end a bag only once. For example, a garbage packet is often disposed of with its content. A bag for packaging a disposable product is often disposed of when it is empty.