Sport climbing is a form of rock climbing that may rely on permanent anchors fixed to the rock for protection, in which a rope that is attached to the climber is clipped into the anchors to arrest a fall, or that involves climbing short distances with a crash pad underneath as protection. This is in contrast to traditional climbing where climbers must place removable protection as they climb. Sport climbing usually involves lead climbing techniques, but free solo and deep-water solo (no protection) climbing on sport routes is also sometimes possible.