SpaceDesk
If, for any reason, you need to extend your desktop to a mobile device (phone, tablet...) this free app is the GoTo in my experience.
It is available both for Android and iOS devices. (PLEASE NOTE: There are some compatibility issues with the latest AMD drivers, as it can be seen in the "Download" section on the main page, read carefully what the developer has to say)
The app offers both connectivity over Local Network Interfaces and Remote Network Connections.
It is pretty straightforward to use, and it is nice for those who want to export instruments from their flight sim to another screen, or use their 10" tablet as a preview window for editing video, or a drawer to put aside all those pesky dockers in Illustrator, Photoshop, InDesign...