Rock climbing can be done indoor and outdoors by climbing on rocks.
Rock climbing is a sport. As with any sport you do not do anything else whilst engaged in that sport. Particularly so with extreme and dangerous sports.
Momentum Indoor Climbing Gym in Sandy, Utah is the largest Indoor Climbing gym.
Some gyms offer indoor rock climbing. Some gyms don't. If you have a gym you want to be a member of call ahead and ask them or check their website. There are also gyms specifically for indoor rock climbing.
As you asked, "The Sport" of rock climbing:1880s : The Sport of Rock Climbing begins in the Lake District and Wales in Great Britain , Saxony near Dresden, and the Dolomites. W. P. Haskett Smith is frequently called the Father of Rock Climbing in the British Isles, and Oskar Schuster was an early climber at Elbsandsteingebirge.For the History of rock climbing:* http://en.wikipedia.org/wiki/History_of_rock_climbingFor indoor rock climbing:The skinny: Rock carvings in China from 300 B.C. depict men climbing rocks, but modern man invented indoor rock climbing. A physical education professor in the UK constructed the first artificial climbing wall in 1964. Since then the sport has taken off in many countries, especially in urban areas where the weather or environment isn't conducive to outdoor climbing. Sounds familiar.* http://www.centerstagechicago.com/recreation/articles/so-you-wanna-rock-climb.html
Rock climbing is not a sport at all nor is it competitive. It would be classes as an activity.
Indoor rock climbing was invented as a way for professional climbers to train during the off season. It gradually has become commercialized and mainstream.
skydiving, bungee jumping, snowboarding, skiing, rock climbing
The cost of indoor rock climbing varies greatly from one gym to another. Most rock gyms, however, offer discounts to those who bring their own equipment.
What are the least dangerous extreme sports? The World's Best Safe Extreme Sports Indoor Skiing – Dubai, United Arab Emirates. Safe Surfing (Flowriding) – Yas Island, Abu Dhabi. Safe Racing Cars – USA. Rock Climbing – Reno, Nevada. Indoor Skydiving (Bodyflight) – Las Vegas, Nevada. Pool Scuba Diving – Montegrotto Terme, Italy.