Why is it important to regularly replace the Audi A2's spark plugs?

I've heard that spark plugs should be changed every few years but I'm not sure why. Can someone explain the impact of old spark plugs on an Audi A2's performance?

Old spark plugs can cause a decrease in fuel efficiency and overall performance, as well as potentially damaging the ignition coils and catalytic converter.

Regularly changing the spark plugs ensures optimal ignition performance and can prevent potential misfires or other engine problems.