Foams are materials that consist of a gas dispersed in a liquid or solid. They are created when air bubbles are trapped within a substance, resulting in a light and airy structure. Common examples of foams include whipped cream, shaving cream, and polyurethane foam used in mattresses and cushions. Foams can be classified into two main types: open-cell foam and closed-cell foam. Open-cell foam has interconnected bubbles, allowing air and moisture to pass through, making it softer and more flexible. Closed-cell foam, on the other hand, has sealed bubbles that provide better insulation and water resistance, making it suitable for applications like buoyancy aids and insulation materials.