The procedure for creating a screenshot on a mobile device depends on what platform it is running on: most often it is either Android or iOS (iPhone). Also, some use smartphones on Windows Phone, which have their own unique ways of taking screenshots.
To take a screenshot on Android, simultaneously hold down the volume down button and the phone's power button (top or side).
After pressing, quickly release the buttons, if a white flash appears, then the screenshot has been successfully generated.
This method may not work on older versions of Android, universal recommendations are described here.
On the latest versions of the iPhone, there is no Home button (a round button in the center under the smartphone display). To take a screenshot on them, you need to simultaneously hold down the camera snapshot button (right) and the volume up button (top left).
После - быстро отпустите обе кнопки. Снимок экрана будет сделан и появится его миниатюра. Если нужно отредактировать изображение - кликните по миниатюре и произведите все необходимые манипуляции.
If it didn't work on your iPhone then take a look other methods.
In Windows Phone 8, you need to press the button under the display and the power button of the smartphone. After - you will hear a click sound, which means the screenshot has been created.
If you have Windows Phone 10 version, then simultaneously hold down the power and volume up buttons.