A sleeping bag is a portable and insulated bedding system designed for outdoor enthusiasts and travelers. It provides a comfortable and warm sleeping environment, even in challenging weather conditions. Sleeping bags are commonly used during camping trips, hiking expeditions, and other outdoor activities.

The primary purpose of a sleeping bag is to keep the user warm by trapping and retaining body heat. They are typically made of lightweight and durable materials such as nylon or polyester, with synthetic or down insulation. Synthetic insulation is known for its ability to retain warmth even when wet, making it suitable for wetter climates. Down insulation, on the other hand, provides excellent warmth-to-weight ratio and is ideal for colder temperatures.

Sleeping bags come in various shapes and sizes to cater to different preferences and needs. The most common types include rectangular, mummy, and semi-rectangular. Rectangular sleeping bags offer more room for movement and can be unzipped to use as a blanket. Mummy-shaped bags, on the other hand, are tapered towards the feet, reducing dead air space and maximizing heat retention. Semi-rectangular bags strike a balance between the two, providing a good compromise between comfort and weight.