Throughout the development of the iOS, there has been a few text bugs that would usually crash the phone. Most of these bugs were found by 4chan, and eventually used by trolls to crash people's iPhones.
The iOS 6 Text Bug is a bug that crashes your iPhone/Mac on iOS 6 or Mac OSX 10.8. It was fixed in iOS 7 and Mac OSX 10.9.
This is the text that crashes it:
سمووحخ ̷̴̐ خ ̷̴̐ خ ̷̴̐ خ امارتيخ ̷̴̐ خ
It will crash and close the application on Safari, it gives an "Aw Snap!" crash error on Google Chrome, however Firefox is immune to it. It is unknown if other browsers is immune to this or not.
This is the text that crashes:
effective. Power لُلُصّبُلُلصّبُررً ॣ ॣh ॣ ॣ 冗
iOS 10 Edit
This is the text that crashes iOS 10: