What type of data type is this ? Question mark

Answer 1

character simply,

also used as ternary operator ( ? :)

also used as wildcard for single instance of any character in shell scripts

many other languages have different uses of it too, like in PHP

Answer 2

? is also usable as a metacharacter for 0 or 1 instance of a group or character class in regex.

Answer 3

'?' is a string.