This talk introduces the James Webb Space Telescope, NASA’s next large astrophysics mission, launched Christmas Day, 2021 and now in science operations. We will introduce Webb’s science goals; detection of the universe’s first light, assembly of galaxies, birth of stars and observation of planets and exo-planets.  How the design responds to mission requirements and produces the performance necessary to achieve the mission’s goals will be discussed.  Many of the unique elements of the architecture will be explored. The main engineering challenges for largest telescope ever built in space are discussed and illustrated. A special emphasis for this discussion will be on the consideration of materials properties. The talk concludes with a brief look at some of the initial science results of humanity’s largest telescope in space.