The lemon (Citrus × limon) is a small evergreen tree native to Asia, and the tree's ellipsoidal yellow fruit. The fruit is used for its juice, and the pulp and rind (zest) are also used in cooking and baking. Lemon juice is about 5% to 6% citric acid, which gives lemons a sour taste. The distinctive sour taste of lemon juice makes it a key ingredient in many drinks and foods, such as lemonade.