Onion is an Allium vegetable scientifically known as (Allium cepa) belonging to the family of Amarydiceae in the order of asparagales. Onion is a biennial plant but is usually grown as an annual. Modern varieties typically grow to a height of 15 to 45cm (6 to 8 inch). It has gained popularity among researcher due to its nutritional and medicinal values. Its nutritional properties include, manganese , vitamin B6, vitamin B9, vitamin C, Copper, dietary fiber, foliate, phosphorus, potassium, sulfur, folic acid. These nutritional properties help to lower cholesterol, thin the blood, and detoxify the body, prevention of cancer, building and maintenance of collagen which provide structure to skin and hair. Medicinally , onion dried bulb, raw bulb, fresh bulb, seeds, shoot, root, leaf juice, are used for the treatment of jaundice, insect bites, asthma, dysentery, fever, high blood pressure, whitlow, boil, eruption, skin disease, urinary problem etc. based on these more research is needed to get more fact about onion(Allium cepa).