Is San Jose CA considered part of Silicon Valley?

Yes, San Jose, CA is considered part of "Silicon Valley." Silicon Valley is an area in the southern part of San Francisco Bay, and includes Santa Clara County, part of Alameda County, part of Santa Cruz County, and part of San Mateo County. The city of San Jose is widely viewed as the capital of Silicon Valley. The nearby cities of Cupertino, Palo Alto, Los Altos, Livermore, Mountain View, Santa Clara, and Sunnyvale are also part of Silicon Valley.