BASE jumping, also sometimes written as B.A.S.E. jumping, is parachuting or wingsuit flying from a fixed structure or cliff. "BASE" is an acronym that stands for four categories of fixed objects from which one can jump: building, antenna, span, and Earth (cliff). Due to the lower altitudes of the jumps, BASE jumping is significantly more dangerous than skydiving from a plane. In the U.S., BASE jumping is currently regarded by many as a fringe extreme sport or stunt. In some jurisdictions or locations, BASE jumping is prohibited or illegal; in some places, however, it is permitted, like Perrine Bridge, in Twin Falls, Idaho, USA. BASE jumping became known to the wider public by depictions of BASE jumping in a number of action movies and was featured in the 2014 documentary "Sunshine Superman".
The acronym "B.A.S.E." (now more commonly "BASE") was coined by filmmaker Carl Boenish, his wife Jean Boenish, Phil Smith, and Phil Mayfield. Carl Boenish was the catalyst behind modern BASE jumping, and in 1978, he filmed the first BASE jumps to be made using ram-air parachutes and the freefall tracking technique (from El Capitan, in Yosemite National Park). While BASE jumps had been made prior to that time, the El Capitan activity was the effective birth of what is now called BASE jumping.
BASE numbers are awarded to those who have made at least one jump from each of the four categories (buildings, antennas, spans and earth). When Phil Smith and Phil Mayfield jumped together from a Houston skyscraper on 18 January 1981, they became the first to attain the exclusive BASE numbers (BASE #1 and #2, respectively), having already jumped from an antenna, spans, and earthen objects. Jean and Carl Boenish qualified for BASE numbers 3 and 4 soon after. A separate "award" was soon enacted for Night BASE jumping when Mayfield completed each category at night, becoming Night BASE #1, with Smith qualifying a few weeks later.