<Tr> <Th> Time zone </Th> <Td> Pacific (UTC − 8) </Td> </Tr> <Tr> <Th> Summer (DST) </Th> <Td> PDT (UTC − 7) </Td> </Tr> <P> Silicon Valley (abbreviated as SV or The Valley) is a region in the southern San Francisco Bay Area of Northern California, referring to the Santa Clara Valley, which serves as the global center for high technology, venture capital, innovation, and social media . San Jose is the Valley's largest city, the 3rd - largest in California, and the 10th - largest in the United States . Other major SV cities include Palo Alto, Santa Clara, Mountain View, and Sunnyvale . The San Jose Metropolitan Area has the third highest GDP per capita in the world (after Zurich, Switzerland and Oslo, Norway), according to the Brookings Institution . </P> <P> The word "silicon" originally referred to the large number of silicon chip innovators and manufacturers in the region, but the area is now the home to many of the world's largest high - tech corporations, including the headquarters of 39 businesses in the Fortune 1000, and thousands of startup companies . Silicon Valley also accounts for one - third of all of the venture capital investment in the United States, which has helped it to become a leading hub and startup ecosystem for high - tech innovation and scientific development . It was in the Valley that the silicon - based integrated circuit, the microprocessor, and the microcomputer, among other key technologies, were developed . As of 2013, the region employed about a quarter of a million information technology workers . </P>

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