What is the purpose of a question mark after a type (for example: int? myVariable)?

Question

Typically the main use of the question mark is for the conditional, x ? \"yes\" : \"no\".

But I have seen another use for it but can\'t find an explanat

Answer 1

practical usage:

public string someFunctionThatMayBeCalledWithNullAndReturnsString(int? value)
{
  if (value == null)
  {
    return "bad value";
  }

  return someFunctionThatHandlesIntAndReturnsString(value);
}