The onion (Allium cepa) is a widely cultivated vegetable known for its distinctive flavor and aroma, which make it a staple ingredient in cuisines around the world. It belongs to the Amaryllidaceae family and is closely related to garlic, leeks, and chives. Onions come in various types, including red, yellow, and white, each offering a unique taste profile ranging from sweet to pungent. They can be eaten raw, cooked, fried, or pickled, and are used to enhance the flavor of countless dishes. Rich in vitamins C and B6, as well as antioxidants like quercetin, onions provide several health benefits, such as supporting immunity, reducing inflammation, and promoting heart health. The distinctive smell of onions comes from sulfur compounds released when their cells are broken, which also contribute to their health-promoting properties.