So, I'm just switching from the iPhone and I am getting used to how the Droid pushes out it's notifications. The iPhone obviously didn't have apps running in the background and it completely relied on push notifications. I am trying to figure out what programs I can kill in Advanced Task Killer that won't block from notifications coming in. Is there any way to tell? One example is Twidroid. Does it require to be running the background for notifications? It worked for the first couple of days, now I get NO notifications. I'm also noticing apps closing without me killing them. Depending on the app, do some kill themselves after so long? My main question though, as I said is: What types of apps require to be running in the background for notifications?