The Jet Propulsion Laboratory in Pasadena, CA, was founded by scientists and engineers from the nearby California Institute of Technology (Caltech) in 1940 as a test site for their early rocket experiments, which were getting too dangerous (and noisy) to remain on the campus. World War II and the subsequent Cold War funneled defense funds to the site, where work turned to producing practical jet engines for military uses in the 1940s and 1950s.
When the Soviets launched their Sputnik satellite in 1957, it was the JPL that developed and launched America's response, Explorer 1. That led to an affiliation with the new National Aeronautics & Space Administration (NASA), which remains in place to this day. Technically, JPL is a NASA facility but is managed by Caltech.
In the 60s and 70s, JPL was at the forefront of the Mariner missions that sent back the first pictures of the surfaces of Venus and Mars, and the Ranger and Surveyor missions that first landed on the moon. Since the 70s, JPL has continued to explore “the final frontier” with a series of missions (Voyager, Cassini-Huygens, the Hubble and Spitzer space telescopes, etc.) that have regularly transmitted valuable information and breathtaking pictures from the different planets in our solar system and beyond. JPL has also allowed scientists to get a better understanding of our own planet with a series of topographic and oceanographic missions.