What is car exhaust?

a car exhaust is the pipe that sticks out of the back or sides of a car. There is a catalyst (an element) inside every exhaust in the world and what it does is act as a filter. For example a car engine produces both carbon dioxide (CO2) and carbon monoxide (CO) and other products but they're not important in this case, a catalyst would hold some of the carbon in carbon monoxide to make more carbon dioxide. This means tat less deadly gases are released.