Mac OS X has a useful hot corner feature, by which you can execute specific commands by moving mouse pointer to the four corners of the screen. One of the uses I personally put it to is to turn off the display.
On Windows, the same functionality can be obtained with the help of a tiny portable free program called Push Monitor Off (PushMonitOff).
PushMonitOff turns off all your displays with a single shortcut. The advantage of this over manually turning off is that you can switch it off and on from the keyboard effortlessly. Besides, if you use a multi monitor system (as many designers, programmers and power users do), then this saves you the hassle of reaching out to each LCD screen to turn to off.
To get the shortcut to turn off computer screen quickly, install the PushMonitOff app, then hit Sift + F1. This shortcut is customizable from Settings accessed via the system tray icon. Any mouse / keyboard movement turns the display on again.
Download Push Monitor Off [download page]
PushMonitOff is actually donationware, so if you liked the software, consider making a small donation (from top left in the above download page).
An original article by TechZilo
How to turn off monitor display with hotkey / keyboard shortcut
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How to turn off monitor display with hotkey / keyboard shortcut