This handy app lets you use an iOS device as a second screen with your Mac. You also get touchscreen features and it's just been updated to include a version of the TouchBar featured on the new MacBook Pro.
Using a second screen while you're working can make you a lot more productive .
There have been plenty of second screen and mirroring apps over the years that haven't really delivered, but this one is sure to surprise. Duet Display has been developed by former Apple engineers and it uses a Lightning cable and a separate (free) desktop app to ensure the quality is what you've come to expect from an Apple device.