Image Source: ehow.com
Another quick tip for iPhone beginners here (veterans please look away). I ‘ve realized recently that even some of my fairly techie friends had not realized how to use the ‘Force-quit ‘ feature of the iPhone.
Force-quit is a way “ the only way “ to make a badly behaving or just plain frozen iPhone application close. It ‘s very simple to do, once you know how, and very useful in several situations.
To use force-quit, when you are in an app that seems to be frozen or is just acting too flaky for your liking, simply hold down the Home button for a little over 5 seconds. You will not get any message or confirmation on screen as to what you ‘re doing, but you ‘ll be dropped back to the Home screen when the force quit is complete.
A few other things worth noting about force-quit:
Again, you ‘ll get no confirmation message when it ‘s done “ you ‘ll just be back at a home screen.
Force-quit can also be useful if you ‘re concerned about certain apps continuing to leave certain processes open and chewing up a bit of your available memory (as in RAM memory that programs run in, not storage memory that music and photos etc are stored in). These are generally only Apple ‘s own apps “ like Safari and Mail “ that have any ability to do this. You might want to force-quit them if you ‘re looking to free up as much memory as possible before running a game, for example, or just to give them a full shutdown to help get past an issue you ‘re having with them.
If you ‘re running one of the iPhone OS 3.0 *beta* versions 1-5, you will not be able to use force-quit “ for some reason it has disappeared from these betas.
If an app absolutely won ‘t respond to a force-quit effort and your whole phone is ‘frozen up ‘ you ‘ll need to do a hard reboot. That is achieved by holding down the Home and Power buttons (as shown in the photo at the top of this post), for a period of 10-20 seconds or until you see the iPhone ‘s screen go black and the Apple logo appear as the start of its reboot process.