Leaving Windows 10 idle for a certain period will probably activate a screen saver. Alternatively, Windows 10 also has a sleep mode that can come on after a period of inactivity. This is how you can always keep the screen on in Windows 10.
First, configure the screen saver settings by entering ‘screen saver’ into Cortana search box. Select Change screen saver to open the window shown below. This includes all the screen saver settings.
Select the Screen saver drop-down menu and click (None) from there. Click Apply and OK to apply the settings. That switches the screen saver off.
However, there are other things that can also switch off the display. To configure those, click Change power settings. Then select Choose when to turn off the display to open the options below. Now select Never from all the drop-down menus there and click Save changes.
You can also keep the display on without configuring any Windows 10 settings with extra third-party software. One of those programs is Caffeine, which you can install from here. Click caffeine.zip there to save its zipped folder. Open the folder in File Explorer, press the Extract all button and then select a path to extract it to. You can run the software from the extracted folder.
Caffeine effectively simulates a regular F15 keypress to keep Windows 10 active. When it’s running, you’ll find the Caffeine icon in the system tray as shown below. You can right-click that icon and select Active to switch it on. You can always switch it off by clicking that option again.
Try it out by selecting a screen saver to come on after a certain period. Then switch on the Caffeine Active option. The screen saver won’t come on at all.
So that’s how you can keep the display on with and without adjusting Windows 10 settings. Both the Caffeine utility and Windows options outlined above will keep the OS active.