Compression takes place after the air has been mixed with fuel. Piston rings fill the role for which they are made, which is to seal the combustion chamber so that maximum power can be obtained from the ignition.
Continuous production of steel is only possible if all systems function properly. Within this entire process of feeding, melting, casting and processing, piston rings play an important role in multiple ways.
Steam is what started the industrial revolution. The steamroller above is a wonderful example of this. However, steam represents much more than that. The applications for steam are still very widespread today.