The main ingredient in Jell-O is gelatin. Gelatin is a protein derived from collagen, which is obtained from the skin, bones, and connective tissues of animals, primarily pigs and cows. It gives Jell-O its characteristic gelling properties, allowing it to set into a semi-solid form when mixed with water and allowed to cool. Jell-O is popular for its versatility and can be made in various flavors and colors, often used in desserts, salads, and candies. It is widely enjoyed for its refreshing texture and is a staple in many celebrations and gatherings.