The UC (University of California) system is comprised of 10 research-oriented universities. The 10 campuses are:Berkeley, Davis, Irvine, Los Angeles, Merced, Riverside, San Diego, San Francisco, Santa Barbara and Santa Cruz.
They are overseen by the Regents of the University of California, or UC Regents. UC is considered autonomous from the state government, even though they draw a large amount of funding from the state and the Regents are appointed by state governors. However, most UC-wide decisions are made at the UC Office of the President (UCOP).
Of special note:
Berkeley was the first campus to be founded (in 1868). The title "University of California" was initially given to an entity on their current campus. Today, the title of "University of California" is prepended to the name of the city in which a campus resides. However, since UC Berkeley happens to be located on land in which early University of California buildings were at, this particular school is often referred to as "California" (or "Cal" for short).
The San Francisco campus enrolls mostly graduate students in medical services. They offer a single undergraduate program in dental science.
The Merced campus is the first research university in the United States to open in the 21st century. It was believed by the Powers That Be in the UC Governance that the Gigantic Davis Freshman Class of 2006 had taken away students who 'should have' gone to Merced.
UC Davis is the northernmost of UC campuses, and is the only one with a College of Agriculture.
The libraries of the UC system collectively hold more volumes than any other library in the United States with the exception of the Library of Congress.
Official website: http://universityofcalifornia.edu/
See also UC System vs CSU system.