For the first, any situation where there isn't a 1:1 coupling of capital and lowercase letters would result in collision or ambiguity upon a .tolower() For the

For the first, any situation where there isn't a 1:1 coupling of capital and lowercase letters would result in collision or ambiguity upon a .tolower() For the second, one OS, locale, and input method may result in Unicode fully-composed forms, and another in fully-decomposed forms. Is ø one code point or two? The answer is: it depends on your software environment. 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. There's actually a pretty good StackOverflow post on dealing with this issue in Python: https://stackoverflow.com/questions/319426/how-do-i-do-a-case-insensitive-string-comparison https://stackoverflow.com/questions/319426/how-do-i-do-a-cas...