Everything has become synchronized. Such is the world these days. Now, you can easily play around with your TV and flick channels at your own free will even if the remote control is stuffed somewhere in those crevices of the couch where it would take eons to be rediscovered.
Moreover, if you need to save something really important on your phone and do not have internet connection or a software that can save that important message/file/etc, you can easily take a screenshot of it and save it for later use.
Every single android device that runs on Ice Cream Sandwich (version 4.0), has the option to take as many screenshots as you can. Moreover, this unique function allows you to save everything that is currently showing on your phone screen — even the buttons.
However, keep one thing in mind that every device has a different way to initiate the screenshot program. For instance, phones running on Windows 8 platform have completely different mechanism when it comes to taking a screenshot as compared to phones that are based on android technology.
Even android phones have different ways to initiate the screenshot program. For instance, Samsung Galaxy S2 and its forerunners' screenshot program can be initiated by simultaneously pressing the power and home button.
Nexus 5 and 4 on the other hand, initiates a screenshot program when you press the volume down and power button. In short, almost every device running on the android platform, uses more or less the aforementioned techniques.