Originally Posted by
sting7k Those apps are not actually "running". They are stored in the RAM in a suspended state. But they are not using CPU or doing anything. Some apps can stream audio or use GPS for example. The only apps that do "run" pretty much fully in the background are the stock apps.
As you open more apps the OS will start to kill some apps in the fast app switcher to free up RAM for active apps to use and to keep things running smooth.
Hope this helps.
That is a nice tip to know.