Irvine () is a master-planned city in 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 212,375 as of the 2010 census; in 2019 the California Department of Finance estimated the city's population at 287,401.
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, the Orange County Center of the University of Southern California (USC), and campuses of California State University Fullerton (CSUF), University of La Verne, and Pepperdine University.
The Gabrieleño indigenous group inhabited Irvine about 2,000 years ago. Gaspar de Portolà, a Spanish explorer, came to the area in 1769, which led to the establishment of forts, missions and cattle herds. The King of Spain parceled out land for missions and private use.
After Mexico's independence from Spain in 1821, the Mexican government secularized the missions and assumed control of the lands. It began distributing the land to Mexican citizens who applied for grants. Three large Spanish/Mexican grants made up the land that later became the Irvine Ranch: Rancho Santiago de Santa Ana, Rancho San Joaquin and Rancho Lomas de Santiago.