Carpets are one of the earliest companions of man. Long before houses and cities were built, men and women in some parts of the world, especially the wandering nomads, devised shelter and protection by erecting temporary habitation with the use of thick bark, wood, hay etc. The cold floor to which the body had to cling at night and get support in day time was first warmed with mats made of grass, reeds, straws etc. until the advent of woven fabrics. Some use the words carpet and rug interchangeably. Historically, however, some have distinguished between carpet and rug based on size (the former being larger) or use (carpets on floors, rugs on beds). For the sake of clarity, some textile scholars also differentiate between carpets and carpeting. The latter are wall-to-wall and are often woven or tufted as roll goods. In the real estate and home improvement industries, a distinction is made between carpet and rug. The former indicates covering that is fixed to the floor and the latter a floor-covering that is loose-laid, mostly for decorative purposes. The hot and dusty weather conditions in India restrict the use of carpets. In India, they are mainly used in commercial buildings for noise suppression and insulation in air conditioned buildings. They are also used for aesthetic enhancement and to aid in interior decoration. They are also used in automobiles.