(Although this is going to be much more specific and less theoretical in the future, I think a little introduction to the philosophy of unreality might be helpful here — to give you at least some idea of the underlying background theory which provides the structure and motivation behind the observations and reflections in this blog.)
We sometimes talk about things that aren't so. It can happen accidentally, when we relate something to someone about which we are actually mistaken, or deliberately, when we're lying. In the latter case, we are typically doing so with the intent to deceive: we know things aren't as we are telling them, but whoever we are talking to doesn't. There are, however, other cases where the receiver is aware of what is and what isn't the case, and actually needs to be — most commonly when what is taken in is a work of fiction, such as a novel or a movie.
In all these situations, we can indicate the divergence of what we are describing from what is the case by using phrases such as: "It wasn't really so — I was mistaken about it", "I was lying — in reality things went differently", "This isn't real — it's just a movie". Terms such as 'real' (and others, such as the 'is the case' or the 'things aren't so' which I used above) have the function to make us aware of that divergence. They're not used in the description, or the telling, of something — they are necessary for saying something about the description, or the telling, namely, that it is not true to what is the case.
In many cases, at least someone knows about the divergence. This is easy to see in the case of lies or fiction. Someone knows that a description has been made up. (At the very least the person who did make it up knows that!) Unless the main goal is deception, there are normally also other signals that can be taken from the context: if you are reading a book with the words 'A novel' on its title page you'll take its contents as a fictional narrative, that is, as about something that didn't really happen.
In theory, if we could develop an account of all the ways (and motives) of making up things, we might be able to approximate the border between reality and unreality — we might be able to map out, as it were, the territory of the real and the adjacent areas of the unreal. (Much philosophical work has been dedicated to this quest over the centuries, mostly coming from a desire to get clear about the concept of reality.) At least we could do so in principle, for very probably in practice many potentially made-up stories will remain that we aren't going to verify (or falsify), and so won't be able to sort them into those which describe things as they are and those that don't — that is, some fuzziness might remain in practice. But the ideal limit of this process should give us a demarcation of reality, as distinguished from unreality.
There may, however, not be a single, reliable criterion (or set of criteria) for determining whether something is really as it is told, or whether it has been made up. Although we seem to have a pretty good idea in many cases, there are probably others where we don't. And there is much diversity among the forms and occasions of talking about things differently than they really are. Perhaps it isn't such a good idea then, to try and draw a line somewhere between what is real, i.e. what makes up reality, and what is not.
It also might be questionable whether reality is that interesting, after all. True, we have an interest, in many situations, not to be mislead, or at least not to be deceived. But if we were to proceed as described above, by studying all the ways of unreality, we would get that (at least as far as would be practicable), even if we didn't succeed eventually in getting a clear grip on reality.
What is more: we have a good starting point in our intuitive ability, in many cases, to tell reality and unreality apart. Looking more closely at these cases, and carefully analyzing the details of what is going on there, seems to be a path that is at least likely to provide some insight — if not about reality, at least about the varieties of unreality.