There are four major types of tea, which are all made from the same plant, Camellia sinensis, a white-flowering evergreen shrub. Although the color of the teas may differ (and correspond to their respective names), the different types are the result of processing. This also affects the flavor and amount of antioxidants each contains. See About Tea for more information.

The four major types of tea are:

• Black tea. Leaves are allowed to completely oxidize during processing, producing a strong flavor with high levels of caffeine. This type of tea has the least amount of catechins (type of phytochemical associated with certain health benefits) due to the more extensive processing. In the Western world, black tea is named for the color of the tea leaves. In China, it is sometimes called red tea for the color of the liquid produced. Most tea consumed in the United States is black tea.
  
  
• Oolong tea. Leaves are partially oxidized during processing. They are usually allowed to oxidize for two to three days, and then the oxidization process is interrupted before it is completed. The amount of processing of leaves falls between that required for black and green teas, although the taste of oolong is more similar to green tea.
  
  
• Green tea. Minimal oxidation occurs, usually through steaming or dry cooking in hot pans. Green tea is usually processed within a couple days of being picked and made from mature tea leaves. Green tea has more antioxidants than black and oolong teas, but less than white tea. It is gaining popularity in the United States.
  
  
• White tea. Made from young leaves that have not turned green (they are sometimes shaded from the sun). Leaves are steamed and dried almost immediately after being picked, and no oxidation is allowed to occur. White tea has the highest level of antioxidants of the four teas. This type of tea is expensive and uncommon outside of China.

Each type of tea may be available with added flavors, herbs or other ingredients (e.g., chamomile, rosehip). For example, Earl Grey tea is a popular blend of black tea and oil of bergamot (orange flavored oil). These flavored varieties are still considered tea as long as they are made from the tea plant.   

Tea may be identified by various names, often according to its location of origin. For example, Ceylon tea is grown in Sri Lanka (formerly known as Ceylon), Yunnan and Lapsang Souchong in China, and Darjeeling in India. India and Sri Lanka have primarily been known for producing black tea, while China has produced most of the oolong and green varieties. However, many countries that typically produced only one type of tea are now producing a variety of types. Thus, Darjeeling or Ceylon teas may be black, green or oolong. 

Herbal tea, sometimes called an herbal infusion or tisane, is made from plants other than the tea plant and, thus, contains no tea. Some herbal teas may contain antioxidants, but not necessarily in the quantity available in products made from the tea plant. For example, tea made from plant Aspalathus linearis (also known as red bush or rooibos), which is native to South Africa, has been gaining popularity in the United States and may also contain antioxidants. Herbal teas are required by the U.S. Food and Drug Administration (FDA) to identify on their labels the name of the plant from which they are made.

There are a great variety of herbal teas. Many are promoted as being associated with certain health benefits. However, the safety and effectiveness of most herbs has not been proven.