The term "carpet" derives from old italian carpita, "carpire" meaning to pluck. The term "carpet" is used interchangeably with the term "rug." but, they are not the same thing. A carpet stretches from wall-to-wall while a rug does not. A wall to wall carpet is a textile floor covering consisting of an upper layer of "pile" attached to a backing. The pile is generally either made from wool or a manmade fibre such as polypropylene, and usually consists of twisted tufts which are often heat-treated to maintain their structure.