An onion is a bulbous vegetable known for its layered structure and strong, pungent flavor. It typically has a papery outer skin that can be white, yellow, or red, depending on the variety. Inside, it is composed of multiple concentric layers of fleshy, juicy, and often slightly translucent sections. When sliced or chopped, onions release sulfur compounds that can cause eye irritation and tears. Onions have a diverse culinary use, offering a base flavor in soups, stews, stir-fries, and sauces, and they can be eaten raw, grilled, fried, or caramelized. Their flavor can vary from mild and sweet to sharp and tangy, depending on the variety and cooking method. Onions are also known for their nutritional benefits, providing vitamins, minerals, and antioxidants.