ASCII and Unicode quotation marks
The fact that ASCII does not have balanced quotes is one of the great catastrophes of computing.  It makes everything more complicated than it needs to be, from embedding code in strings to parsing CSV files, to regexps.  For example, if I want to embed a quoted string in another quoted string, I have to escape the inner quotes like so:"This is string containing an embedded \"quoted\" string"Then I have to think about whether or not the system I'm going to send that string to is going to "helpfully" remove the backslashes, in which case I need to write:"This is a string containing an embedded \\"quoted\\" string"God help you if you want to go two levels deep.All this horrible complexity could have been avoided if we could just write:«This is a string containing an «embedded» quoted string»Alas.