Over time, course design has become increasingly more focused on the safety of the horse and rider. Fences are built more solidly than in the earlier days, encouraging a bold jump from the horse, which actually helps prevent falls. The layout of the course and the build of the obstacles encourage the horse to have a successful run. This includes greater use of precision fences, such as corners and "skinny jumps", that are very good tests of the rider's ability and the horse's training but allow the horse to simply run around the jump if the rider misjudges it. Safety measures such as filling in the area between corner-shaped jumps on cross-country or rails of a fence help prevent the entrapment of the legs of the horse decrease the number of serious falls or injuries.