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.
Interrogative
Another common way of marking questions is with the use of a grammatical particle or an enclitic, to turn a statement into a yes–no question enquiring whether that statement is true. A particle may be placed at the beginning or end of the sentence, or attached to an element within the sentence. Examples of interrogative particles typically placed at the start of the sentence include the French "est-ce que" and Polish "czy". (The English word "whether" behaves in this way too, but is used in indirect questions only.) The constructed language Esperanto uses the particle "ĉu", which operates like the Polish "czy":