JWST is humanity’s premier infrared space observatory. Featuring a 6.5-meter gold-coated beryllium primary mirror and a 5-layer tennis-court-sized sunshield, Webb operates at cryogenic temperatures (~40 K) in an orbit around Sun-Earth L2. Its instruments resolve the earliest stars and galaxies formed after the Big Bang, map exoplanet transmission spectra, and peer through dense stellar nurseries.