Usually when you need to share the image of your computer screen then you capture the screen using a dedicated ‘Print Screen’ button of your computer keyboard. Similarly, there’s a built in hidden trick in iPhones and iPod Touch to capture the screen in a jiffy.
For capturing images of your iPhone screen, all you need to do is just press the Sleep/power button (on the top edge) of your iPhone/iPod touch and simultaneously press ‘Home’ button. Instantly you will hear a clicking sound with slight flashing on your iPhone screen and the image will be automatically saved on the photo roll of your iPhone that you can later share or email to a friend. And yes, it doesn’t matter whether you are playing a game or browsing internet on Safari, the above trick works for capturing screen of what ever application you are using.