For practical purposes the State of California is divided into travel regions to help you understand the diversity of this great state. It's length spans over 1,000 miles and wide just less than half that amount, but the geography and weather varies tremendously depending on where you are.
Yes, California is one of the most diverse states in the U.S., and many consider it a state unto itself, with assets and an economy that equals many countries.
The regions include 12 geographic areas, three made up counties--Los Angeles, Orange and San Diego. They are some of the most populated areas, thus they garner their own region category. Other regions are delineated more by their geographic and weather or topography attributes such as High Sierra, Deserts, Central Coast, North Coast and Shasta Cascade. Gold Country is one of the most interesting regions because it comprises places where gold was discovered in California just as it became a state around 1849-1850 date.
Then there's the Inland Empire, which includes mountain and ski resorts, the primary Southern California wine country region, and inland weather with some ocean influences and also desert climates.
Last but NOT least is San Francisco Bay Area, which now includes the moniker "Silicon Valley". San Francisco gets the most publicity but Silicon Valley has most the population and power base, comprised of technology companies that are world forces!