Absolutely one of my must-install app on Android. Greenify!
It’s specially great if you have a lot of apps installed and they are taking up too much of your battery.
What does it do?
Greenify help you identify and put the misbehaving apps into hibernation when you are not using them, to stop them from lagging your device and leeching the battery, in an unique way! They can do nothing without explicit launch by you or other apps, while still preserving full functionality when running in foreground.
It’s Free and its Awesome!