First re-flight of orbital class rocket

Last Thursday, +SpaceX successfully re-launched and landed the first stage of a Falcon 9 rocket on the drone ship Of Course I Still Love You. This is the first re-flight of an orbital class rocket in human history (sorry Blue Origin, you don’t count) and a major milestone for the space industry. The ability to re-use the most expensive part of a rocket promises to drastically reduce the cost of future spaceflight.