BASE jumping is a sport involving the use of a parachute to jump from fixed objects. "BASE" is an acronym that stands for the four categories of fixed objects from which one can jump:
B uilding
A ntenna (an uninhabited tower such as an aerial mast)
S pan (a bridge or arch)
E arth (a cliff or other natural formation)
The acronym "BASE" was coined by film-maker Carl Boenish, his wife Jean Boenish, Phil Smith, and Phil Mayfield. Carl was the real catalyst behind modern BASE jumping, and in 1978 filmed the first BASE jumps (from El Capitan, in Yosemite National Park) to be made using ram-air parachutes and the freefall tracking technique. 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 jumping is significantly more dangerous than similar sports such as skydiving from aircraft, and is currently regarded by many as a fringe extreme sport or stunt.