This link will tell you all you need.
Summary for archival sakes:
It's called the conditional operator. It's a ternary operator that
takes three terms:
BooleanExpression ? Expr1 : Expr2
The BooleanExpressionis evaluated. If it's true, the value of the
whole expression is Expr1. If it's false, the value of the whole
expression is Expr2.
So it serves the same kind of purpose as an if statement, but it's a
term rather than a whole statement. That means you can embed it in
places where you can't use a whole statement.
