Split screen modes divide your computer screen into two different halves, so you can view two different windows at the same time. This is immensely useful for research projects and more complex work assignments (especially on laptops), which is why so many students and professionals hunt down ways to split their screen whenever they get a new computer.
More: Your Mac has a hidden screenshot program — here’s how to find it
Now for the good news: Thanks to past MacOS updates, there’s a very easy split screen mode called split view that anyone with an updated Mac can use. Let’s go over how to do it!
Split view requirements
The split screen capability was introduced in Mac OS X 10.11 El Capitan. By now, a few additional updates of MacOS have come and gone, and split view remains available in all newer versions of the operating system. If for some reason you have a Mac that hasn’t been updated to El Capitan, you won’t be able to use the split screen option (although frankly, that’s probably the least of your worries at this point).
Exceptions: Not all apps work with split view. You’ll know if it doesn’t work, because the window will just go to full screen and refuse to split no matter how you try. It’s hard to tell if an app works in split view until you try it. However, most Apple-sponsored apps tend to come with split view capabilities. Third party apps are less likely to have the option—for example, some Microsoft Office apps don’t support split view at the moment, which can be a little frustrating.
Get started with split view
Begin by opening the Mac windows that you want to divide into a split screen. Browser windows, app windows, doc windows—any type will work (except for the aforementioned caveats). Pick one window to start with, and look in the upper right corner. You should see three red, yellow and green dots that can be used to control the window.
If you hover over the right-side green dot, you’ll see it has two small expand arrows. This is the button you want. Hold down on the green dot, and the window will expand/contract as needed, then slid into one half of your screen. Do not tap the green button, because this puts the window into fullscreen 
mode instead.
One half of your split view is done! Now select your other window that you want to split view. This window should automatically shift to cover the other side of your screen, completing the split view experience. You can tap either window to switch focus back and forth as needed.
Note: With touchpads and Magic Trackpads, it’s a little harder to “hold down” the split screen button. With most setups you can hold down the button by setting two fingers on the trackpad and using a third finger to click on the split view button, which acts as a long-term press down. You may need to dive into your trackpad settings to see just how to do this. The important thing to remember is that it is possible.
Adjusting split view
Your split view doesn’t have to be a half-and-half deal. Instead, you can choose which window gets more screen time. Look for the thin black bar in the middle of the screen. Click and hold that bar, and you can move it right or left to give either window more real estate. This is particularly useful if you’re trying to view a large web page with odd design, or need extra space for a big spreadsheet, etc.
If you realize you prefer the windows on different sides, then click and hold one window, and drag it over to the opposite side. The windows will automatically switch places.
Also, keep in mind that shuffling between screens can get a little confusing when you’re first learning how to use it. You may find a couple windows vanished to your dock or to a side menu by the time you’re done. Don’t worry, you probably didn’t lose anything permanently, just keep looking for where Apple put it.
Exiting split view
Nothing could be simpler! When you’re ready to leave split view mode, just tap on either green dot in either window. This will return both windows to their original state and allow you to resume what you were doing before you needed split view.
A quick word about Mission Control
Do you have a lot of windows open and once and want something more comprehensive than split view to look at them all? Mission Control can help. This mode shows you all the windows you have open in a top bar while also giving you an at-a-distance look at all the windows currently on your screen.
You can access Mission Control in many ways, but one of the easiest is to simply drag a window up to the very top of your screen, which should automatically enter Mission Control mode (alternatively, Apple keyboards typically come with an F3 Mission Control button). You can enter Mission Control while in split view if you want, which is an easy way of switching split view windows as is necessary.