Free solo climbing
Free solo climbing (or free soloing) is a form of rock climbing in which the climber (or free soloist) climbs on technical terrain without ropes or any form of protective equipment — all they are allowed to use are climbing shoes and climbing chalk (or ice tools and crampons if ice climbing). Free soloing is the most dangerous form of climbing, and, unlike bouldering, free soloists climb at heights where any fall can be fatal.