Silicon Valley is a region in Northern California that is a global center for high technology and innovation. Located in the southern part of the San Francisco Bay Area, it corresponds roughly to the geographical area of the Santa Clara Valley. The term "Silicon Valley" refers to the area in which high-tech business has proliferated in Northern California, and it also serves as a general metonym for California's high-tech business sector. The cities of Sunnyvale, Mountain View, Palo Alto and Menlo Park are frequently cited as the birthplace of Silicon Valley.
https://en.wikipedia.org/wiki/Silicon_Valley