Push-ups are a functional, compound exercise which work multiple muscle groups if performed properly.
Check out this instruction video here The best Push Up technique.
In particular doing push-ups will increase your strength and muscle definition in your arms, shoulder, upper back and core, How good is that! plus… your cardiovascular system will also be enhanced as multiple muscles are used which means your heart has to work harder to deliver oxygen rich blood to the muscle tissues.
Another great benefit of performing push-ups is it helps improve your posture and stabilise your upper back muscles as the muscles responsible for supporting your posture are strengthened.