Question mark
In the early 13th century, when the growth of communities of scholars (universities) in Paris and other major cities led to an expansion and streamlining of the book-production trade, punctuation was rationalized by assigning Alcuin's stroke-over-dot specifically to interrogatives; by this time the stroke was more sharply curved and can easily be recognized as the modern question mark.
Tag question
In most languages, a tag question is set off from the sentence by a comma(,).
In Spanish, where the beginnings of questions are marked with an inverted question mark, it is only the tag, not the whole sentence, which is placed within the question bracket: