Question

Is there a difference in the shade of meaning between 'It's dark' and 'It's dark out'?
What is 'out' mean??

Answer 1

I think in this case 'out' means outside.

Answer 2

Like Emoticon said, the "out" in "it's dark out" means the outside. A little more clarification that if one simply said "it's dark", it implies it's dark wherever he or she who said it is. However, "it's dark out" implies it's dark outside of wherever he or she is.