It's not rare to see a wine's country of origin listed as "California." A country into itself in the wine world, California makes enough varieties and styles to match many European wine countries. While it must settle for being only a state, that does not affect the high quality and diversity of its wines.
The most famous of the California wine regions is Napa Valley, and these wines are certainly outstanding – but watch out, because Sonoma County is catching up to its overshadowing neighbor. Down south, the Santa Barbara's Santa Maria Valley is finding that some Rhône style grapes and even Pinot and Chardonnay are able to do well. The Central Coast, the largest California AVA, has many different microclimates that lead to a wide range of wines with many sub-AVAs.