Greenify is a simple application that boosts the performance of your smartphone and tablet by hibernating apps running in the background. There are some applications that you shouldn't hibernate like your antivirus, alarm, instant messaging apps. In terms of user interface, this tool rocks and intuitive and straightforward layout where you can quickly browse through your apps library and add those which are not that important for you.
Hibernation means that the processes running in the background won't use your CPU and battery no more, but as it was mentioned already, you must avoid apps like your alarm because you rely on them to function all the time. This tool also comes with a feature which analyzes your installed applications and shows events when your device will be less performant because of them.
Another important feature is the automated hibernation and you can configure it to activate a couple of minutes after screen of your device goes off.