A catalytic converter is a part of your car's engine exhaust system. Catalytic converters contain rhodium, platinum, and palladium - precious metals more valuable than gold. For this reason, thieves steal them to sell the precious metals they contain. These parts can cost upwards of $2,000 to replace.
Three ways to protect against catalytic converter theft:
Stay vigilant - typically, catalytic converters are removed with grinding tools or sawzalls which create loud noise. Suspicious activity can be reported to police by calling 9-1-1.