The automotive body determines the outward appearance of the vehicle. Car bodies are designed for a number of factors, the major three being style, room for people/mechanical components, and aerodynamic efficiency. Sometimes there are openings in the body where air can enter the car for various purposes like cooling and ram air.
Bodies are made out of a variety of materials (one vehicle's body may even have parts made from many different materials) such as steel, aluminum, fiberglass, and carbon fiber. Racing cars often use lightweight materials, while family cars are built with stronger metals. Most vehicles have bodies that come in many pieces so that only a portion will need replacing if it gets damaged. Some car enthusiasts buy aftermarket body kits and components that give the vehicle a different appearance than the manufacturer's original design.