Tea is a beverage made by steeping processed leaves, buds, or twigs of the tea bush, Camellia sinensis, in hot water for a few minutes. The processing can include oxidation, heating, drying, and the addition of other herbs, flowers, spices, and fruits. The four basic types of true tea are (in order from most to least processed): black tea, oolong tea, green tea, and white tea. The term "herbal tea" usually refers to infusions of fruit or of herbs (such as rosehip, chamomile, or jiaogulan) that contain no Camellia sinensis . (Alternative terms for herbal tea that avoid the word "tea" are tisane and herbal infusion.) This article is concerned exclusively with preparations and uses of the tea plant C. sinensis. Tea is a natural source of the amino acid theanine, methylxanthines such as caffeine and theobromine, and polyphenolic antioxidant catechins. It has almost no carbohydrates, fat, or protein. It has a cooling, slightly bitter, and astringent flavor.