The most innovative technology in the 21st century.
As of the 21st century, SpaceX operates one of the most innovative technologies, or perhaps the actual most innovative technology, for their reusable rockets. SpaceX's Starship which is currently in development as of September 2020, is a fully reusable rocket.
When the entire rocket reaches space, the first stage/booster stage will obviously detach from the spaceship part. It has enough fuel left to literally fire up its engines to perform a re-entry burn to slow it down before fully re-entering the atmosphere, and then performing a landing burn to land right next to the launchpad where it launched from, to be re-used.
The actual spaceship itself, which is still in space, now in Earth Orbit, will wait there in orbit, while the booster gets ready to launch again, with a Starship Tanker on top of the booster, instead of the spaceship. The Starship Tanker will launch to orbit, just like the actual spaceship did on top of the same booster, and they will attach to each other and the tanker will refuel the spaceship, so it can depart for the Moon, Mars, and beyond. The booster will land AGAIN to be reused for another tanker for another spaceship, or another spaceship, repeating the entire process, depending on the destination for the spaceship.
This is the most innovative technology on Earth. Well, and Mars. Venus and Mercury too, all of them! Feel free to click hereto watch the Starship Launch animation to see what we just talked about in action.