BASE jumping involves parachuting from fixed objects like buildings, antennas, bridges (spans), and cliffs or mountains (earth). It is considered the most extreme form of skydiving. BASE is an acronym that stands for the four objects jumped from - Building, Antenna, Span, and Earth. Antennas are a popular object to jump from because they are tall like buildings but easier to access with less security. Earth jumps can involve cliffs, mountains, or canyons, with El Capitan in Yosemite often viewed as the birthplace of BASE jumping. However, it is an extremely dangerous sport with significant risks of fatality.