Dark tea is a type of tea that has undergone a secondary fermentation process, which distinguishes it from other types of tea. It is also known as heicha in China and post-fermented tea. Dark tea is aged, and the aging process involves pile fermenting (oxidizing) and pine fire drying, which changes the chemistry, flavor, aroma, and appearance of the leaf. The specifics of aging are closely guarded trade secrets. Dark tea can be light to full-bodied, and it is smooth, with a noticeable sweet, floral flavor. The aroma of dark tea may be slightly earthy, but this typically does not carry over to the flavor. Dark tea is often made with a little more leaf per cup than other teas, and it is steeped in 208-212 degree water for 4-6 minutes. The leaves may be re-steeped for multiple infusions.

Puer tea is the most common type of dark tea known, and it is one of the oldest types of tea, with a history dating back more than 2,000 years. Most dark teas come from three counties (Anhua, Yiqang, and Linxing) in Hunan Province of China. However, China also has quite a few heicha selections from other regions outside of Puer, such as Hunan Heicha, Sichuan Heicha, Liu Ancha. Dark tea is one of the first teas to travel the ancient trading routes of the Tea Road and the Silk Road into eastern Russia.

Dark tea has possible medicinal applications, and it has been found to help reduce the risk of diabetes.