Silicon Valley is a nickname for the southern portion of the San Francisco Bay Area of Northern California in the United States. It is home to many of the world's largest high tech corporations, as well as thousands of tech startup companies. The region occupies roughly the same area as the Santa Clara Valley where it is centered, including San Jose and surrounding towns. The term originally referred to the region's large number of silicon chip innovators and manufacturers, but eventually came to refer to all high-tech businesses in the area, and is now generally used as a metonym for the American high-technology economic sector. Silicon Valley is a leading hub for high-tech innovation and development, accounting for one-third of all of the venture capital investment in the United States. Geographically, Silicon Valley is generally thought to encompass all of the Santa Clara Valley, the southern San Francisco Peninsula, and southern portions of the East Bay.