You can pin any Apps to the left or right-hand side of the screen. For example, open any app and then press the Windows Key + . (period) to move that app to the right-hand side of the screen, pressing the same keys again will move it to the left-hand side, and pressing the same keys again will make it full screen. While an app is pinned, any other app or program can be opened and loaded into the available space on the screen.
Any open app can also be pinned by using your mouse by clicking at the top of the tile and dragging it to the left or right-hand side of the screen.