I'm a interactive designer working on Android projects. One question I'm having in my mind is that, Are Buttons Really A Must? Because I see developers starting to design APPs with build-in menu button and back button on screen. They are trying avoid the hardware buttons on the cellphone and maybe eventually create new android that is more and more like iPhone--A phone with only one home button. So someone please tell me, are menu button and back button a must in Android design? Is there some kind of mandatory from Google that hardware buttons are key features of Android? Please let me know!!!