Silicon Valley is a region in the southern part of the San Francisco Bay Area in Northern California that serves as a global center for high technology, innovation, and social media. It corresponds roughly to the geographical Santa Clara Valley, although its boundaries have increased in recent decades. San Jose is the Valley’s largest city, the third-largest in California, and the tenth-largest in the United States. Other major Silicon Valley cities include Palo Alto, Menlo Park, Redwood City, Cupertino, Santa Clara, Mountain View, and Sunnyvale.
The word “silicon” in the name originally referred to the large number of innovators and manufacturers in the region specializing in silicon-based transistors and integrated circuit chips. The area is now home to many of the world’s largest high-tech corporations, including the headquarters of more than 30 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 Silicon Valley that the silicon-based integrated circuit, the microprocessor, and the microcomputer, among other technologies, were developed. As of 2013, the region employed about a quarter of a million information technology workers..[source: wikipedia]