Chipping is a rock climbing technique that uses a hammer and chisel to create artificial hand-holds on natural rock. The hammer and chisel may be substituted for any other tool that can take off layers of a rock to create a different feature on the rock. Within the climbing community this is an extremely controversial topic because it permanently modifies the natural features of a rock face. While in the past the practice was accepted or ignored, as more people have become climbers and environmental concerns have grown, there has been a trend against chipping. This process can also be referred to as "manufacturing" holds.