Did you experience while checking email and while waiting to finish downloading new emails, you press the Home button and open other applications like for example Safari browser or notes and after some time the vibration and alert sound for new email will come up? As like any other UNIX machine, iPhone is capable of doing multiple tasks at the same time. Cool!

Now, the problem is how you can assure that there is no other unneeded applications are running (except the phone process) that will surely waste your battery?

For example, while listening to your iPhone’s iPod – you don’t want your browser or weather continuously run on the background – as this time you really only want to listen to your music.

Here’s what I discovered:
Pressing the Home button only suspends the current application and returns you to the Home screen. For example, if you just finished composing an email; while sending it, and you press your Home screen; email still continuously run (sending) in the background. That means pressing Home button not really kills the application or even the process but it stays in the background until maybe all the tasks are completed and hopefully with some idle time it will close automatically.

When you are at your Home screen, and you know that you are not browsing Safari, or sending/receiving email, or downloading new maps locations or weather – how you can make sure that those applications are properly exited or no other undesired apps running that will consume your CPU cycles in the background?

Simple! Just press and hold the Home button for 4 to 8 seconds – the active application screens clears – as it quits all processes in the background and you return to the Home screen.

This is also helpful for example once you experience like the apps that you are running hang-up or stops responding – pressing and holding the Home button for 4 to 8 seconds will kill that rogue apps and will return you back to Home screen – I read this somewhere long time before, I think in the manual and they called it “soft-reboot”.

Keeping your iPhone free from undesired applications running in the background will makes your iPhone cooler and it should be lesser strain in your battery.