This isn't one of our favorite things to do, but sometimes it's necessary because your iPhone completely locks up on you. Perhaps its a bad App, or some crazy compatiblitiy thing, but whatever it happens to be, there will probably be a time when your iPhone locks up and you can't do anyhtnig to exit the App. This is especially true as your iPhone begins to show its age.
What do you do? Hard reset. Again, we tend to use this one as a last resort, but it will usually fix things when it's absolutely necessary.
Here's what you do:
Hold the Sleep Button and the Home Button down. You will the prompt for "Slide to Power Off" (which they patented, by the way).
Ignore the prompt and continue holding the two aforementioned buttons. Eventually, your iPhone will just power off.
Know that this works with all iDevices. This means your iPad, iPhone and iPod Touch. We haven't had to use it on the other devices yet, but that may be because the iPhone gets the most daily use out of us.