Virtual desktops let you segregate your open apps into discrete areas, literally multiple, virtualized versions of your PC's desktops. Switching between open virtual desktops is easy enough using Task View (the button that looks like two panels, one over the other, in the taskbar) or 'Win+Tab', while 'Alt+Tab' jumps you between open apps across all desktops. There's also a way to actually shift an open app from one virtual desktop to another if you'd like to shuffle things around.
First, head to the virtual desktop housing the app you'd like to move to another virtual desktop, then open the Task View interface. Just click and hold on the app you'd like to move, then drag it to the desired virtual desktop at the bottom of the screen. You can also drag it to the '+New Desktop' option in the lower-right corner to create a new virtual desktop for the app.