Free solo climbing (or free soloing) is a form of rock climbing where the climber (or free soloist) climbs on technical terrain without ropes or any form of protective equipment — they are allowed to use 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. Though many climbers have free soloed routes with technical grades that they are very comfortable on, only a tiny group free solo regularly, and at technical grades closer to the limit of their abilities.
The international profiles of some climbers have been significantly increased by their free soloing activities, such as Alex Honnold, Alex Huber, Alain Robert and John Bachar, but others question the ethics of this, and whether the risks that they are undertaking should be encouraged and commercially rewarded. While "free solo" was originally a term in climbing slang, after the popularity of the 2018 Oscar-winning film Free Solo, Merriam-Webster added the word to their English dictionary in September 2019.
