|question mark (?)|
|Definition - The punctuation mark that replaces the period at the end of an interrogative sentence, but which can also be used within a sentence to express doubt.|
1. Use it to express editorial doubt (i.e. to show that there is either missing data or that you're not sure that the data is correct).
Bob Smith (1940?–2007)
2. Place question marks inside quotation marks or parentheses only when they are part of quoted or parenthetical matter.
Mason replied, “What is the truth of the matter?”
Have you seen Coppola's movie “The Conversation”?
3. Don't add additional punctuation marks after a question mark that is enclosed in quotation marks.
“Where are you going?” she asked. (good)
“Where are you going?,” she asked. (bad)
4. Don't put a comma after a question mark that is within quotation marks.
He said, "Are you going?", and then he left. (bad)
He said, "Are you going?" and then he left. (good)
5. Don't use it for indirect questions.
She asked where he went. (good)
She asked where he went? (bad)
6. You can use it mid-sentence to mark an interrogative phrase. In this case, it functions like a comma.
Where shall we go? and what shall we do?
Etymology - The word question derives from the Latin quærere, ask or seek.
Note: Some claim that the symbol ? was created by combining the first and last letters of the Latin quaestio, a seeking or an inquiry.
Oxford English Dictionary - The first citation for this name for the symbol is from — believe it or not — 1905:
"A question-mark is sometimes placed in the middle of a sentence. In such a position it concentrates attention on certain elements of the thought."
(T. F. & M. F. A. Husband Punctuation ii. vi. 74)