> If you don't normalize your input, you could have a situation where an account created on, say, Win XP, might be inaccessible for the average user from iOS.

> If you don't normalize your input, you could have a situation where an account created on, say, Win XP, might be inaccessible for the average user from iOS. This only applies if you handle the normalization in the front-end. But you should normalize it in the back-end, right? Or am I missing something here? Edit: Answered further down by wongarsu