What is Falcon 9, the rocket taking Shubhanshu Shukla to ISS?

The Axiom-4 Mission launched from NASA's Kennedy Space Center in Florida today (June 25) with the Falcon 9 rocket taking Shubhanshu Shukla and the other members aboard the SpaceX Dragon craft to outer space. But what do we know about the Falcon 9? How does it work?

Explainers