A paper clip is usually a thin wire in a looped shape that takes advantage of the elasticity and strength of the materials
of its construction (usually steel or some other metal, but sometimes plastic) to compress and therefore hold together
two or more pieces of paper by means of torsion and friction. Some other kinds of paper clip use a two piece clamping system.
Recent innovations include multi-colored plastic-coated paper clips and spring-fastened binder clips.