The San Francisco Bay Area, commonly known as the Bay Area, is a populated region that surrounds the San Francisco and San Pablo estuaries in Northern California. The region encompasses metropolitan areas of San Francisco, Oakland, and San Jose, along with smaller urban and rural areas. The Bay Area's nine counties are Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara, Solano, and Sonoma. Home to approximately 7.15 million people, the nine-county Bay Area contains many cities, towns, airports, and associated regional, state, and national parks, connected by a network of roads, highways, railroads, bridges, tunnels and commuter rail. The combined urban area of San Jose and San Francisco is the 53rd largest urban area in the world.

The Bay Area is anchored by three major cities. San Francisco is the cultural and financial center of the metropolitan area and Northern California, and is famous for its iconic skyline, steep hills, cable cars and historic streetcars, Fisherman's Wharf, and the Golden Gate Bridge. It is the second-most densely populated major city (population greater than 200,000) in the United States. The largest city in the Bay Area in land area and population is San Jose, which is located in the South Bay and is part of the world renowned technology hub known as Silicon Valley. Oakland, the third most populous city, is a central hub for the East Bay, major industrial center and contains the Port of Oakland, the fifth busiest intermodal container port in the United States. The region's northern counties encompass California's famous Wine Country, home to hundreds of vineyards and wineries while the region's Pacific Ocean coastline hosts numerous beaches.