Silicon Valley, an industrial region, approximately 20 mi (32 km) long, in the Santa Clara Valley between Palo Alto and San Jose, mainly in Santa Clara and San Mateo counties, W central Calif., where many computer manufacturing and design companies are located. Computer-software and other high-technology industries are also there. The name derives from high-purity silicon used in making the semiconductors used in computers.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.