Sleeping Bags

The sleeping bag is a protective "bag" for a human to sleep, basically a blanket that can be closed with a zipper or similar means, and functions as a bed in situations where it is impractical to carry around a full bed (i.e. when camping, hiking, hill walking or climbing).
So it is a important camping equipment.
Its main purpose is to provide warmth and thermal insulation. It also protects, to some extent, against wind cold weather, precipitation, and exposure to view, but a tent performs those functions better. The bottom surface also provides some cushioning, but a sleeping pad is usually used in addition for that purpose. A camping sack is a rainproof cover for a sleeping bag that may be used in place of a tent for lightweight camping trip travelers or as a backup if inclement weather occurs.