As Flyingbronco05 says, it is an arrival route to IAD
. A STAR is a "Standard Terminal Arrival Route" and is designed to get an airplane close to the airport without much assistance from ATC. It is not an approach, per se, but an arrival route. From the end of the arrival route ATC will give vectors, turns and altitude changes, to the crew to line them up with the final approach, usually an ILS.