The Bay Area contains many cities, towns, airports, and associated regional, state, and national parks, connected by a complex multimodal transportation network. The Bay Area is known for its natural beauty, progressive politics, prominent universities, technology companies, and affluence. Other definitions may be either smaller or larger, and may include neighboring counties that do not border the aforementioned estuaries, such as the Central Coast counties of Santa Cruz, San Benito, and Monterey, or the Central Valley counties of San Joaquin, Merced, and Stanislaus. The Association of Bay Area Governments defines the Bay Area as including the nine counties that border the aforementioned estuaries: Alameda, Contra Costa, Marin, Napa, San Mateo, Santa Clara, Solano, Sonoma, and San Francisco.
The San Francisco Bay Area, commonly known as the Bay Area, is a region of California centered around the San Francisco, San Pablo, and Suisun estuaries in Northern California.