There are several ways to split a screen in Windows 10, but the easiest is with Snap Assist. This feature has to be enabled in Start > Settings > System > Multitasking, although it should be enabled by default.

Snap Assist lets you drag a window to a corner or side of the screen to “snap” it there, which in turn makes room for other apps to be snapped in the resulting empty screen space.

To split your screen in Windows 10 with Snap Assist using the mouse:

  1. Open five windows and/or applications. (This is a good amount to practice with.)
  2. Place your mouse on an empty area at the top of any open window, hold down the left mouse button, and drag the window to the left side of the screen, toward the center of that side.
  3. Let go of the mouse. The windows should take up half the screen, although in some cases it snaps to the top left; it just takes practice.
  4. Click any window that now appears on the right side of the screen. It will position itself to take up the other half.
  5. With two windows side-by-side, drag the dividing line that separates them to resize both windows simultaneously.
  6. Access and then drag any other open window to the right side of the screen. It will likely snap into the top right corner.
  7. Continue to experiment with dragging and dropping each of the open windows. Click any smaller window to bring it to the forefront.
  8. Drag any window to the top of the screen to maximize it.