Exactly, it's this simple. I also like another definition proposed here by another commenter: "the ability to experience positive and negative mental states".

Exactly, it's this simple. I also like another definition proposed here by another commenter: "the ability to experience positive and negative mental states". I don't understand the confusion about the definition of consciousness. It's actually the one thing that is most obvious, because it's right there all the time. This is like trying to define the experience of seeing "blue" or any other qualia. It's impossible because it's subjective, but we can all agree that we each have an experience of seeing blue.