Question mark

The question mark (?) is a punctuation mark that is used at the end of a sentence when asking a question.

The symbol is thought to come from the Latin quæstio, meaning "question", which was shortened to Qo. The uppercase Q was written above the lowercase o, and this mark was turned into the symbol that we use today.

Another guess about where question mark comes from says that it comes from the 9th century, when it was a point followed by the curved part written slanted.

Some writers put a space between the end of their sentence and the question mark. This is thought to come from a French practice and is called French spacing. In French a space is always put before question marks, exclamation marks, colons, and semicolons. In English, however, using this space is thought of as bad form. Some English books do have these spaces, but are often a very thin space, which are not full spaces but an attempt to make the words easier to read.

 Computing 
In computing, the question mark character is represented by ASCII code 63, and is located at Unicode code-point U+003F. The full-width (double-byte) equivalent, ？, is located at Unicode code point U+FF1F.

On Macs, a folder with a flashing question mark on startup means there is no operating system found or the startup disk has failed or there is no hard drive inside the computer.

 Examples of the question mark being used 
"What time is it?"
"How are you doing?"
"Why did that happen?"

Sources
Lupton, Ellen and Miller, J. Abbott, "Period styles: a punctuated history", in The Norton Reader 11th edition, ed. Linda H. Peterson, Norton, 2003 Online excerpt (at least) 
 Parkes, M.B., Pause and Effect: an Introduction to the History of Punctuation in the West, University of California Press, 1993
Truss, Lynne, Eats, Shoots & Leaves Gotham Books, NY, p. 139
 References 

Category:Punctuation
Category:Typography