Silicon Valley, a region in California centered in Santa Clara county, including the cities of San Jose, Palo Alto, Sunnyvale, Cupertino, Los Gatos, and Menlo Park. The valley was named from the mass production of electronic products made from silicon-based semiconductors in the region.

Silicon Valley is one of the world's chief centers of technology industries. Companies involved in the research, development, and manufacturing of microelectronics have been present in the region since the last half of the twentieth century. Many software companies, internet-related businesses, and companies in the fields of biotechnology and aerospace are also here. Companies such as Apple Computer, Hewlett Packard, and Intel have corporate headquarters in Silicon Valley.