Depending on the resolution of your screen, you can have up to four apps on a screen at a time. You can schedule meetings on your calendar while you respond to email, or record a lecture in class with Sound Recorder while you take notes...
http://www.ebrahma.com/2013/10/using-apps-side-by-side-windows-8-1-and-windows-rt-8-1/Labels: fit-two-apps-at-a-time, Sound-Recorder, Start-and-open-a-third-app, To-open-a-third-app, To-use-two-apps-side-by-side, Using-apps-side-by-side-Windows-8.1-and-Windows-RT-8.1, window-8, window-8.1, window-RT