Why are phones so fragile?

[CaliGurl4ev]

I know dropping phones cause them to break but why? What is the process of them breaking? Is there a wire that's lose that when dropped, it completely breaks off? Or maybe something cracks which causes the phone to shut down? What specifically causes a phone to break why being dropped on a surface?

If you have sources to back up your thoughts (this is for a science fair project by the way), you probably will get 10pts Just sayin'

Thanks in Advance