Foam substance is a material that consists of a mass of small bubbles or cells filled with gas. It is created by trapping air or other gases in a liquid or solid matrix, resulting in a lightweight and often flexible structure. Common examples of foam include polyurethane foam, used in mattresses and cushions, and styrofoam, which is often used for packaging and insulation. Foams can be classified into two main types: open-cell and closed-cell. Open-cell foam has interconnected bubbles, allowing air and moisture to pass through, making it softer and more compressible. In contrast, closed-cell foam has sealed bubbles, providing better insulation and resistance to water, making it suitable for applications like buoyancy aids and insulation materials.