Your engine has several different kinds of filtration systems to keep impurities out of things like fuel, oil or air. They all need to be refreshed regularly so they can continue to keep their respective systems functioning properly.
The cabin air filter purifies air the air that driver and passengers breathe while inside the vehicle. It’s usually located under the dashboard or behind the glove box and keeps dust, pollen and even obnoxious scents from overpowering the cabin environment.
Similarly, the engine air filter cleanses the air that comes in through your vehicle’s front grille. A dirty filter can reduce engine efficiency, causing it to use more fuel. Your engine filter can typically be replaced every 20,000 miles or so, while your cabin air filter can go as long as every 30,000 miles.