The symbol is sometimes thought to originate from the Latin quaestiō, meaning "question", which was abbreviated during the Middle Ages to Qo. The uppercase Q was written above the lowercase o, and this mark was transformed into the modern symbol.
Another hypothesis about the origin of the question mark proposes that it originated in the 9th century, when it appeared as an exclamation point with a curved bar (like a tilde written slantwise) in order to reflect the intonation of the speaker. The name "question mark" was coined in the late 1800s.
Yet another view is that the question mark simply inverts the semicolon, which marked interrogative clauses in Ancient Greek (while enlarging the upper portion).
The origin of the question mark has also been associated with early musical notation like neumes.