The exact number of catalytic converters in a car will vary depending on the type and age of the vehicle. Generally, most vehicles made after 1975 have at least one catalytic converter. Some newer cars may have up to four of them to meet emissions requirements.
Catalytic converters are part of the exhaust system and are usually located after the exhaust manifold and before the muffler. They act as filters to reduce pollutants released into the atmosphere by the exhaust gases of the engine.