The Atacama Large Millimeter/submillimeter Array (ALMA) is a revolutionary instrument in its scientific concept, its engineering design, and its organization as a global scientific endeavor...Currently under construction in the thin, dry air of northern Chile's Atacama desert at an altitude of 5,000 meters above sea level, ALMA will initially be composed of 66 high-precision antennas working together at millimeter and submillimeter wavelengths, with a possible extension in the future.