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
A tag question (also known as tail question) is a grammatical structure in which a declarative or an imperative statement is turned into an interrogative fragment (the "tag"). For example, in the sentence "You're John, aren't you?", the statement "You're John" is turned into a question by the tag "aren't you". The term "question tag" is generally preferred by British grammarians, while their American counterparts prefer "tag question".