Nordic skiing comprises different types of bindings classified according to several standards. They must be adapted to the technique used, the skis, and the boots. Some skis come with plates inspired by alpine bindings into which the attachment system slides and can be adjusted. The heel and toe pieces are thus connected by this plate that lifts with the boot in walking mode. Other bindings, lighter and more efficient, are screwed onto the skis and lock in with a spike system at the front of the boot, leaving the heel completely free.