Berkeley ( /ˈbɜrkliː/ BURK-lee) is a city on the east shore of the San Francisco Bay in Northern California, United States. Its neighbors to the south are the cities of Oakland and Emeryville. To the north is the city of Albany and the unincorporated community of Kensington. The eastern city limits coincide with the county line (bordering Contra Costa County), which generally follows the ridge line of the Berkeley Hills. Berkeley is located in northern Alameda County. The population was 112,580 at the 2010 census. The city is named after Bishop George Berkeley.

Berkeley is the site of the University of California, Berkeley, the oldest of the University of California system, and the Lawrence Berkeley National Laboratory. It is also home to the Graduate Theological Union. The city is noted as one of the most politically liberal in the nation, with one study placing it as the third most liberal city in the United States.

The site of today's City of Berkeley was the territory of the Chochenyo/Huchiun band of the Ohlone people when the first Europeans arrived. Evidence of their existence in the area include pits in rock formations, which they used to grind acorns, and a shellmound, now mostly leveled and covered up, along the shoreline of San Francisco Bay at the mouth of Strawberry Creek. Other artifacts were discovered in the 1950s in the downtown area during remodeling of a commercial building, near the upper course of the creek.

California (pronounced ⁱ/kælɨˈfɔrnjə/) is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third most extensive (after Alaska and Texas). It is home to the nation's second- and sixth-largest census statistical areas (Los Angeles Metropolitan Area and San Francisco Bay Area), and eight of the nation's fifty most populated cities (Los Angeles, San Diego, San Jose, San Francisco, Fresno, Sacramento, Long Beach and Oakland). The capital city is Sacramento.

California's diverse geography ranges from the Pacific Coast in the west, to the Sierra Nevada mountains in the east – from the Redwood–Douglas-fir forests of the northwest, to the Mojave Desert areas in the southeast. The center of the state is dominated by Central Valley, a major agricultural area. California contains both the highest and lowest points in the contiguous United States (Mount Whitney and Death Valley), and has the third-longest coastline of all states (after Alaska and Florida). Earthquakes are a common occurrence due to the state's location along the Pacific Ring of Fire: about 37,000 are recorded annually.