BASE jumping is the recreational sport of jumping from fixed objects, using a parachute to descend safely to the ground. "BASE" is an acronym that stands for four categories of fixed objects from which one can jump: buildings, antennae (referring to radio masts), spans (bridges), and earth (cliffs). Participants exit from a fixed object such as a cliff, and after an optional freefall delay, deploy a parachute to slow their descent and land.

Fausto Veranzio is widely believed to have been the first person to build and test a parachute, by jumping from St Mark's Campanile in Venice in 1617. However, these and other sporadic incidents were one-time experiments, not the systematic pursuit of a new form of parachuting.

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 which were 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.

After 1978, the filmed jumps from El Capitan were repeated, not as a publicity exercise or as a movie stunt, but as a true recreational activity.

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