Meet the Simplified Snapping Tool of Windows 10
Want to have multiple windows automatically fit on your work screen?
Snapping in Windows 7 and 8 involves opening the last window you touched plus the current window you’re working in, but it won’t fit both windows to your screen to see the content in both.
In Windows 10, the snapping tool is a keyboard shortcut that will give you a choice of which window you want to snap based on all the windows you have open and will fit both windows to the screen. Here is a preview: