A chassis (pronounced like CHASS-ee) is the main framework or skeleton that supports a vehicle or machine. Think of it as the bones of a car, truck, or robot: everything else gets attached to the chassis.

In a car, the chassis is the strong metal frame that holds the engine, wheels, seats, and body panels in place. Race car engineers spend enormous time designing the perfect chassis because it affects how the vehicle handles, how safe it is, and how fast it can go. A weak chassis makes for a dangerous, wobbly vehicle, while a strong, well-designed chassis creates a solid foundation for everything else.

You'll also hear chassis used for other machines and electronics. A computer chassis is the metal case that holds the motherboard and other components. A robot chassis is its base structure that the motors, sensors, and circuits attach to. Whether you're building a go-kart, assembling a computer, or designing a Mars rover, you start with the chassis: the fundamental structure that makes everything else possible.