How to explain Bitcoin to your grandmother

Ok, so that's the opening gist of it, and I'm really not sure how many grandmothers would understand this. Even if they did though, the first question that would pop into their wise heads is "Ok my dear, it's all very well to have a clever system like this to validate transactions undertaken in this currency, but you still haven't explained why Bitcoin has value." Right on Gran. That's a much more subtle question entirely. I have my theories about that, and particularly about the quasi-mystical underground hype that initially gave bitcoin value (see the section called 'The mojo of Nakamoto). If I were you, I'd take a seat and listen to the words of warning your gran may have. Bitcoin indeed is pretty amazing, but it has also attracted a lot of hype from a lot of ideologues. I'd recommend ignoring them and taking time to think clearly about this yourself.