Originally Posted by beej231
Somewhere here I read that an app killer or task killer isn't necessary and actually may be harmful on Android devices. I was using one and found that I constantly had all kinds of apps opened that I hadn't used. I stopped using the app killer and it appears that when I leave an app it does not stay open and I have not seen apps running in the background that I have not used. GOOD ADVICE
Some apps run services in the background. so they stay open. A Task Killer will show you this while Fire's application listing wont. I always ignore the services. The only apps I had trouble closing is Doggcatcher and Mantano but I know how to fix that now.