The University of Colorado Boulder (CU Boulder, CU, or Colorado) is a public research university in Boulder, Colorado, United States. Founded in 1876, five months before Colorado became a state, it is the flagship university of the University of Colorado system. CU Boulder is a member of the Association of American Universities, considered a Public Ivy and is classified among R1: Doctoral Universities – Very high research activity.

The university consists of nine colleges and schools and offers over 150 academic programs, enrolling more than 35,000 students as of January 2022. In 2021, the university attracted the support of over $634 million for research and spent $536 million on research and development according to the National Science Foundation, ranking it 50th in the nation. It receives the most NASA astrophysics technology grants of all academic institutions and is the only university in the world that has sent instruments to all planets in the solar system.

The Colorado Buffaloes compete in 17 varsity sports and are members of the NCAA Division I Big 12 Conference. The Buffaloes have won 28 national championships: 20 in skiing, seven total in men's and women's cross country, and one in football. The university has produced 10 Olympic medalists. Alumni, faculty, and researchers have included 12 Nobel Prize laureates (of whom 5 were affiliated with the university when the prizes were awarded), 10 Pulitzer Prize winners, 11 MacArthur "Genius Grant" recipients, 1 Turing Award laureate, 20 astronauts and 2 associate justice of the United States Supreme Court.