The primary ingredient in a balloon is latex, a natural rubber derived from the sap of rubber trees (Hevea brasiliensis). Latex provides balloons with their flexibility, elasticity, and durability, making it possible to inflate them without bursting. Additionally, some balloons are made from mylar, a type of polyester film that allows for printed designs and metallic finishes. Latex balloons are biodegradable, which can be an environmental consideration, while mylar balloons can be reused but take longer to decompose. Balloons are widely used for decoration and celebrations, and they can come in various shapes, sizes, and colors, contributing to their popularity for parties and events.