Depending on how many cylinders your car's engine has - you have this many spark plugs. We recommend we check these approx every 3rd Service, unless specifically required sooner - or asked by the customer.
Picture #two is from a BMW - 2001
The top Spark Plug is worn, and the bottom is the new replacement spark plug.
"What is a Spark Plug & what does it do?
An internal combustion engine requires three key ingredients to operate: air, fuel and spark. A spark plug is a critical engine component that provides the spark that ignites the air-fuel mixture that drives an engine" . Source NGK.co.nz