Overview: The Ultraviolet Explorer (UVEX) is targeted to launch in 2030 as NASA’s next Astrophysics Medium-Class Explorer mission. UVEX will undertake a synoptic survey of the entire sky in the near-UV and far-UV, probing the dynamic universe with a sensitivity more than 50 times better than GALEX. UVEX will also have a powerful broadband spectroscopic capability. UVEX will address fundamental questions from the Astro2020 Decadal Survey, and study the evolution of low-metallicity, low-mass galaxies. UVEX time-domain surveys will probe the aftermaths of gravitational wave-discovered compact object mergers, discover fast UV transients, and diagnose the early stages of explosive phenomena.