I do not know if this is fact or my opinion but- holding the sleep and home button is a soft reset. Because it's the minimal intrusion into the system. A hard reset is through settings, reset, "reset all settings" and "erase all content and settings" because these affect more of the system. Myself, any issues I've encountered typically get resolves with the first one, if not have definitely been resolved by the second. Ive never had a issue get resolved by the first one that cannot get resolved by the second first. Im not picking for an argument, just want to point out their are the different types of resets as options for folks. Just an example: i had a iPhone 3GS that always functioned well. On a random morning where i did nothing different my battery started discharging rapidly. I mean several dozen times more than normal. It went from full charge to 20% or so in a couple hours with almost no use. I did the sleep/ home button reset with no change at all. Skeptical,(about not loosing important data) i did the "reset all settings" and that brought the phone back to normal.