I'm curious about this hackathon culture, because it has clearly become a real thing, but I have only a hazy concept of what's involved, why people would want to do it, or how people are communicating about them. I've never heard an announcement of one, an invitation to participate in one, or seen any advertising about them. How do people find out about hackathons? To whom are they advertised? Who chooses to participate in them? And what is the point of it all?