Due to different growing conditions within the state, the California wine producing areas are separated into five major regions: North Coast, Sierra Foothills, Central Coast, Central Valley, and Southern California. Each of these regions can be divided even further into sub-regions called appellations (which are often counties) that many people who are not even familiar with wine will easily recognize by name such as Napa, Sonoma, and San Joaquin Valley. When a wine label contains a specific appellation, it means that at least 75 percent of the grapes used within the wine were grown within that specific region. Wine labels can also contain two or three appellations to classify the different grapes used within the wine if the percentages are specifically noted as well.

The climate range in California varies from region to region which allows for superb production of many different types of perfectly grown grapes which results in many different varietals. Elements of the weather, such as the cool offshore breezes that cool the Sonoma County vineyards, are extremely important in the distinct growing condition needs for specific wine grapes.

The most important varietals produced in the California wine region are chardonnay and cabernet, though many other varietals from the region are massively popular such a pinot noir. The California wine region has a reputation for producing a high-quality wine to be enjoyed in a relaxed setting among friends, just the way its biggest fans would want it.