A catalytic converter is a device in a vehicle's exhaust system designed to reduce harmful emissions by converting toxic gases into less harmful substances through chemical reactions. It typically sits between the engine and the exhaust pipe. The converter contains catalysts, usually platinum, palladium, and rhodium, coated on a ceramic honeycomb structure that facilitates these reactions. The main functions of a catalytic converter are to:

• Reduce nitrogen oxides (NOx) into nitrogen and oxygen gases, which are harmless.
• Oxidize carbon monoxide (CO), a poisonous gas, into carbon dioxide (CO2).
• Oxidize unburnt hydrocarbons (HC) into carbon dioxide and water.

This process involves reduction and oxidation reactions, helping to cut pollutants by over 99% when properly functioning with a correct air-fuel ratio. Catalytic converters play a crucial role in decreasing smog, acid rain, and health hazards caused by car emissions, thereby protecting both the environment and public health.