A very important part of one's camping gear, sleeping bags are available in various sizes. Built from material that is somewhat water repellant, with insulation in between to keep the sleeper warm. Sleeping bags are available at many different rates, the exact price depends on the brand and also what material has been used to construct a specific one.
Sleeping bags have been around in various forms since the ages. Initially, it was a flat blanket or leather sheet that was closed on 3 sides to tuck a person in, keeping them warm and clean while the slept. As we have moved into a settled way of life the use of a sleeping bag is more common when one is outdoors.
Sleeping bags now are built with insulation and from materials that would fare better outdoors. The outer layer is water repellent to a degree. It is generally understood that a sleeping bag would be used with a tent. Even under it, some people use a sleeping pad or camp cot for additional comfort and safety from water. The inside is filled with down feathers or synthetic materials to keep the person sleeping warm. The synthetic material is useful as it stays warm evenly and can provide some warmth even when soaked. This latter use may save a persons life in the extreme cold.
Synthetic bags weigh a bit more and cannot be compressed as much as down feathers.
It is common to find a sleeping bag that has a tapered design, meaning it becomes narrower towards the foot-end. This helps with heat retention. Also, a lot of bags do not have a zipper all the way to the feet, as the zipper is the weakest point in the insulation.
Compression from storage can cause dead spots as the inner material is thinned out too much to help retain heat well. Therefore, it is better to hang out a sleeping bag for long term storage, with the hanging positions being changed too.
Sleeping bags are available at many different prices, depending on the brand and material. Generally, even a decent quality one is a costly buy given what it is.