The jet engine was developed independently by Sir Frank Whittle in the UK and Hans von Ohain in Germany during the late 1930s. Unlike propeller-driven planes, which are limited by the speed of sound, jet engines work by compressing intake air, mixing it with fuel, and igniting it to produce a high-speed exhaust that thrusts the plane forward. The first jet-powered flight occurred in Germany in 1939 with the Heinkel He 178. After WWII, jet technology revolutionized commercial aviation, leading to the 'Jet Age' of the 1950s and 60s. It made international travel significantly faster, safer, and more affordable, effectively 'shrinking' the planet and making global business and tourism possible for the masses. The jet engine remains the gold standard for high-speed, long-distance transportation.