The part "Case-insensitive comparison requires case folding" says there is an algo for that, but it's up to the language to implement it. E.G: in Python 3, it'

The part "Case-insensitive comparison requires case folding" says there is an algo for that, but it's up to the language to implement it. E.G: in Python 3, it's recommend to use str.casefold() instead of str.lower() for this: >>> "Straße".upper().lower() 'strasse' >>> "Straße".lower() 'straße' >>> "Straße".casefold() 'strasse' >>> Depending of the context, a little str.strip() and/or a str.split() + str.join() may also help. User usually don't want to consider blanks when entering data (e.g: an address), while it's important for machines (e.g: a password). Now like @lmm said, this only normalize the codepoints. Meaning is of course, impossible to be sure that way.