Screenshots is nowadays a basic feature that is included in Stock firmwares(ROM). Most big players like Samsung, Sony, Motorola, etc. include a stock method to click screenshots on your android device. These methods are usually have to be found out by accident as they aren’t usually listed anywhere in manuals or documentations.
I’ve made a list of Different Manufacturers and the methods to click screenshots in them. These methods are generally applicable to all phones of the manufacturers however some exceptions always remain.
For Samsung you have to press and hold the power button + home button together till the screen flashes and gives you a notification on the notification bar. If you don’t succeed in first attempt then give it another try. This works on all Samsung phones running on gingerbread and above.
2. Sony Ericsson
In most Sony phones screenshot is captured by Pressing and holding the volume down button + the Power button for about 2 seconds. The screen will flash and show you a preview of the screenshot as well as give you a notification in the notification bar. This method works for phones running ICS.
For GB users simply press and hold the power button and press the screenshot button in the power menu.
For users running ICS in their Moto device are fortunate as the method for the same is extremely easy. Just press and hold the Volume down button + the Power button for about 2 seconds. However there is a small design fault in this method as in phones like the MOTO RAZR it can be rebooted by pressing the same combination of keys for 10 seconds, so every time you reboot it will generate a useless screenshot. Also sometimes the timing for pressing these keys needs to be perfect, else it will just lock your phone or reduce the device volume.
All 2011 and later phones have a simple method to click screenshots in HTC devices. Simply press the Power button and Home button at the same moment to click a screenshot.
Just like any Android device it is extremely simple to click screenshots on any iDevice. All you have to do is press and hold the home button and then just click the power button once and then your screen will flash and will save an screenshot of the screen.
If you can’t find your device’s method in the list above then you may use an app for the same.