With the ADS-B Interface users can connect AirScope to their local receiver and display traffic data as it's being broadcast.
On top of that, with the built-in complimentary cloud based ADS-B, users can see real traffic from various places in the world (anywhere where there's voluntary coverage) even without being there or having a receiver themselves.
AirScope is a plane plotter that retrieves aircraft positions and measurements from online sources and displays them on top of a world map in radar / ATC style.
The data is retrieved from the online and public info servers of the respective networks (for which an Internet connection is required) at periodic intervals and traffic is plotted accordingly.
When flying online with VATSIM or IVAO (or even as preparation for a flight in one of these networks) it's often useful to have an overview of who's in the air at any given moment or which ATC positions are currently filled and online.