"Android's L release has a new approach to notifications. In Jelly Bean, Google allowed developers to add expanded information and functionality to notifications. Now, users can access their entire notification list directly from the lock screen. You can swipe down to expand the notification panel to get more information. You can also swipe up to unlock the device. Google also introduced heads-up notifications that allow developers to add a small box that appears above full-screen apps that users can expand, act on, or dismiss without leaving the app they're in or opening the full notification shade."
'via Blog this'