Citrus limon is both a small evergreen tree and the tree's oval yellow fruit. The fruit is used for culinary and nonculinary purposes throughout the world – primarily for its juice, though the pulp and rind (zest) are also used, mainly in cooking and baking. Lemon juice is about 5% to 6% (approximately 0.3 Molar) citric acid, which gives lemons a sour taste, and a pH of 2 to 3.
Lemon juice is widely known as a diuretic, antiscorbutic, astringent, and febrifuge. It in hot water has been widely advocated as a daily laxative and preventive of the common cold, but daily doses have been found to erode the enamel of the teeth. Prolonged use will reduce the teeth to the level of the gums. Lemon juice and honey, or lemon juice with salt or ginger, is taken when needed as a cold remedy.