I overheard someone who was trying to "fix" a co-worker's Android phone the other day. "Look at all the apps you have running! You need to download AppKiller to have it quit your background apps." Doesn't iOS do this natively? Downloading another app to kill idle apps seems counter-productive to me.

On the iPhone, double tap the home button and the apps running in the background will show up. Hold your finger on one on the apps till the minus sign appears and then delete them. It will help with battery life.

Here's a good explanation.

Here's a good link from that link.

Unless the app was designed to stay running, Background State Apps, or is poorly written it won't drain the battery in the background. It will free up RAM but there is no real advantage to that, if the OS needs more RAM it will selectively purge it. I imagine FIFO. Unless it is a Background State App it won't be using CPU/battery.

I had one app for finding restaurants that stayed active, using network data. The Location Services arrow in the upper right was always on so I went through the list of recents and found the app causing it by doing the procedure Papa outlined.

The advantage to keeping them open and stored in RAM is that they launch quicker.

You can quit all at once on the iPhone if it's jail broken.

I am not a power user by any means. I usually clear mine at the end of the day if I remember to. If my nephews, nieces, or grandson has had my phone, they will have played every game on there when they are done.

My three year old nephew blows me away at Temple Run.