Skeleton involves a person riding a small sled down a frozen track while lying face down (video below).
The sport is a more intense form of luge because skeleton competitors leap onto the sled and slide downhill head first.
Skeleton athletes experience forces up to 5g, so the helmet is a critical component for both safety and attitude.
Here's a look at some of the riders at the Sochi Olympics:
REUTERS/Murad Sezer Canada's Sarah Reid speeds down the track during an unofficial women skeleton progressive training at the Sanki sliding center in Rosa Khutor, a venue for the Sochi 2014 Winter Olympics near Sochi, February 5, 2014. REUTERS/Murad Sezer When metal sleds were first produced on a large scale in 1892, the frames resembled a human skeleton, hence the etymology of the sport. REUTERS/Murad Sezer Katie Uhlaender of the U.S. starts an unofficial women skeleton progressive training at the Sanki sliding center in Rosa Khutor, a venue for the Sochi 2014 Winter Olympics near Sochi, February 5, 2014. REUTERS/Murad Sezer Skeleton made only two appearances at the Olympics in the 20th century, 1928 and 1948. REUTERS/Murad Sezer Canada's John Fairbairn speeds down during an unofficial men's skeleton progressive training at the Sanki sliding center in Rosa Khutor, a venue for the Sochi 2014 Winter Olympics near Sochi, February 5, 2014. REUTERS/Murad Sezer It was not until the 2002 Winter Olympics in Salt Lake City that skeleton was reintroduced to the Games for good. REUTERS/Murad Sezer Canada's Eric Neilson speeds down during an unofficial men's skeleton progressive training at the Sanki sliding center in Rosa Khutor, a venue for the Sochi 2014 Winter Olympics near Sochi, February 5, 2014. 
Skeleton at Sochi is February 13 and 14. The gold medal favorites are Elizabeth Yarnold of Britain and Martins Dukurs of Latvia.
Here's a video of showing the 2013 Veissmann Luge World Cup held in Park City, UT, where there Americans earned spots to the Olympic team.