In size , shape , colour, and flavour, onions vary. Red, yellow , and white onions are the most common varieties. The taste of these vegetables can vary, sometimes depending on the season in which people grow and eat them, from sweet and juicy to sharp, spicy, and pungent. Potential health benefits are offered by onions. This can include reducing the risk of multiple cancer forms, improving mood, and preserving the health of the skin and hair.