Irvine () is a master-planned city in central Orange County, California, United States, in the Los Angeles metropolitan area. The Irvine Company started developing the area in the 1960s and the city was formally incorporated on December 28, 1971. The 66-square-mile (170 km2) city had a population of 307,670 at the 2020 census. As of 2023, it is the second most populous city in Orange County, fifth most in the Greater Los Angeles region, and 63rd most in the United States. A number of corporations, particularly in the technology and semiconductor sectors, have their national or international headquarters in Irvine. Irvine is also home to several higher-education institutions including the University of California, Irvine (UCI), Concordia University, Irvine Valley College, and campuses of California State University, Fullerton (CSUF), University of La Verne, and Pepperdine University.