The University of Arizona (Arizona, U of A, UArizona, or UA) is a public land-grant research university in Tucson, Arizona. Founded in 1885 by the 13th Arizona Territorial Legislature, it was the first university in the Arizona Territory.

The university is part of the prestigious Association of American Universities (AAU), which represents the 65 leading public and private research universities in North America. It consistently ranks in the top 40 universities nationwide in research spending over the last decade according to the National Science Foundation. The university is classified among "R1: Doctoral Universities – Very High Research Activity". The University of Arizona is one of three universities governed by the Arizona Board of Regents. As of 2021, the university enrolled 49,471 students in 19 separate colleges/schools, including the University of Arizona College of Medicine in Tucson and Phoenix and the James E. Rogers College of Law, and is affiliated with two academic medical centers (Banner – University Medical Center Tucson and Banner – University Medical Center Phoenix). In 2021, University of Arizona acquired Ashford University, a former for-profit college with more than 30,000 students and rebranded it as The University of Arizona Global Campus.

Known as the Arizona Wildcats (often shortened to "Cats"), the UA's intercollegiate athletic teams are members of the Pac-12 Conference of the NCAA. UA athletes have won national titles in several sports, most notably men's basketball, baseball, and softball. The official colors of the university and its athletic teams are cardinal red and navy blue.