If you want to save a picture of your phone's screen, you have a range of options. Without fail, rooting and installing a screen capture app works. But if you haven't rooted your phone, there are still plenty of options.
It could be that the screen capture option is actually baked into your phone. On most Android Froyo devices, for example, you can perform a screen capture by holding the back button and pushing either the power button or the home button. On Gingerbread devices, you can perform a screen capture by holding the power button and then quickly pressing the home / back button. Honeycomb provides NO native screen capture and you must root the tablet in order to take a screenshot, unless your tablet happens to run Sense 3.0, in which case all you have to do is hold down the power and home buttons simultaneously. On Android Ice Cream Sandwich, taking a screenshot is as easy as holding the volume up and the power buttons.
If, for some reason, you're unable to take a screenshot using one of those methods, you can also download the app No Root Screenshot It. The app costs $5 but it supposed to work on ALL phones and allows you to crop the screenshot, draw on it or shake to take the screenshot.
If NONE of these free methods work, we compiled an (albiet limited) list of screenshot options for select devices below. Let us know if there's another method for taking screenshots on YOUR device!
Samsung Galaxy Nexus
Hold down the power button and the volume up button.
Samsung Galaxy S2
Hold down the power and home buttons.
Hold the back button and push the power button.
Hold the back button and push the power button
Hold the back hutton and push the power button
Hold down power button and press home.
Hold down the back button and press home.