Thanks! I had no idea how to kill the running apps on my iPhone. That's probably why I was charging my battery every day.
You probably have to charge your battery daily because you use the phone or apps a lot. It has absolutely nothing to do with how many apps are "running" on the phone.
Apple's multitasking is sophisticated. When most apps are "backgrounded" (ie, you open another app and the current app goes away), the app is essentially put into "suspended animation." It doesn't sit there and run and wait for input. There's no reason for it to, because the screen is currently dedicated to another app! The app does take up RAM, but it doesn't use any extra battery power.
Some apps, the ones that are specifically programmed to act that way, do run in the background. Ie, Pandora can keep streaming music while it's backgrounded. These apps will use battery life as long as they are running. For these apps, obviously you'd want to pause them or make sure they aren't doing anything when you background them.
As far as tstarks' comment about having to close out apps to free up memory, that's not really necessary. iOS automatically closes out apps as needed to free up memory. If you load an app that needs a crapload of memory, iOS will close apps that are using memory in order to allocate it to the primary application. There may be a slight sluggish feeling at first when the app loads and iOS automatically closes out other apps, or perhaps if the app is trying to allocate a large chunk of memory and iOS needs to close out apps to free up memory.
(tstarks - your anecdote about your kid playing with your iPad is a mix of placebo effect and your generally crappy attitude towards everything iOS)
iOS's multitasking is truly beautiful. It doesn't let most apps just sit there running (and doing nothing!) in the background. It only lets them run in the background if they are specifically needing to do so. It also automatically manages memory (as described above.) It's really great. That's why iOS doesn't need stupid memory managers.
. Apple has an impressive lead, and growing sales. Yet their total sold is a smaller percentage of the tablet market each year.
Have you read any of the tech news released in the last week? The iPad is killing everything else.