Batteries are potentially volatile things, stuffed with electrochemical cells practically humming with electrolytes. Every once and a while, then, they’re sure to break down, and companies like Apple do literally everything in their power to make sure it doesn't happen.
Here’s why. An iPhone 5c that exploded in the pocket of a 13-year-old girl resulted in a fire so severe that she was rushed to the hospital with second-degree burns.
The iPhone was in the girl’s back pocket at the time, so it appears that the failure of the two-month iPhone might have been due to stress. She may have cracked it sitting down.
As a bigger guy who stuffs his iPhone in his own back pocket, I should probably pay attention to this girl’s misfortune before I set my ass on fire.