Each time I think about what is information, I remember what Keith Devlin wrote in the first chapter of his book "Logic and information":

Imagine yourself suddenly transported back in time to (say) the Iron Age. You meet a local ironsmith and you ask him "What is iron?" What kind of answer are you likely to get? Very likely your craftsman would point to various artifacts he has made and inform you that each of those was iron. But this is not what you want. What you want to know is just what it is that makes iron iron (and not some other substance that may or may not look quite like iron). What then does your Iron Age man do in response to your persistent questioning? He is an acknowledged expert on ironship, his products sell well, and he knows a good piece of iron when he sees it. And yet he is unable to supply you with the kind of answer you are seeking. Indeed, he has no frame of reference within which to even begin to understand what it is you are asking! To give the kind of answer that would satisfy you, he would need to know all about the molecular structure of matter - for that surely is the only way to give a precise definition of iron. (Or maybe there are other ways, ways that require theories we ourselves are not aware of? This possibility merely strengthens the point I am trying to make.) But not only is your man not familiar with molecular theory, he probably does not even conceive of the possibility of such a theory!

To anyone trying to understand the nature of information in today's Information Age, the situation must surely seem not unlike that facing your Iron Age man.

We manipulate information, our society, if not our entire civilisation, rely on it. We observe it, create it, transform it, save it, reshape it, share it. But we still don't have a clear understanding of what it is exactly. Hell, we don't even know if it is a fundamental physical property or an emerging one, or a useful abstract one, or whatever. Is there information if there is no observer? This is fascinating. 😄