is a keyword which causes execution of your method to end there and then, and control to go back to the method which called it, just as if execution had reached the closing '}' of the method.
You can return a parameter by specifying it after the return statement.
private void MyMethod(int value)
if (value < 0)
If you call MyMethod with a positive or zero parameter, it will print the value.
If you call it with a negative value it will not print anything.