Rosemary is an herb. It is native to the Mediterranean region but is now grown worldwide. The leaf and its oil are used to make medicine. Rosemary is used for improving memory, indigestion (dyspepsia), arthritis-related joint pain, hair loss, and other conditions, but there is no good scientific evidence to support most of these uses. In foods, rosemary is used as a spice. The leaf and oil are used in foods, and the oil is used in beverages.