This is the thrilling story of how test pilots in the USA and UK first pierced the sound barrier in the late 1940s. Much has happened since then, and as recently as 2003 thousands of fare-paying passengers were routinely enjoying intercontinental air travel at speeds of up to Mach 2. The author describes in accessible style the rules and technologies of supersonic flight, ongoing developments in engine and airframe technology, the age of supersonic passenger transports like Concorde, and advances in supersonic fighter and bomber design.