This trick is something you can do on the iPad as well, and it’s very useful especially during the times when you have to write things down on one platform while reading from something else.
To start using this feature on your MacBook, you must first verify if your device is running on El Capitan OS.
If it is, and you have a window open on your screen — click and hold the green button on the upper left hand corner of the window that you have opened. You will witness this window shrink, and you will notice that one side of the screen is highlighted blue. You can move the shrunken window to whichever half of the screen you want it on by simply dragging it with one finger held down.
And then you can open the window that you wish to take the other half of your screen. It’s actually pretty simple.