[And then there's a pause as she decides on what's most important.] I'm not sure if you're familiar with the concepts of multiple universes or alternate dimensions, but this is sort of like that. Each universe is constructed to fit a type of story - superheroes, dinosaurs, zombies, etc. And there is a point in space and time that ties them all together - a nexus point. So of all the people you see writing here (me, Donna, anyone else that shows up) some of us are in the same place, but some of us are in different places. Like we're in New York and you aren't.
The nexus point has taken the form of an old-fashioned hotel. If you see people talking about "the hotel", that's what they mean. Each of the universes can be accessed through a door along one of the hotel's corridors. Some doors are dangerous and some are nearly impossible to find your way out of again, so if you go exploring, it is recommended to be very careful. And we can talk to each other like this. Some people have actual journal books to write in, some people have smartphones or computers or tablets. Some people have other things, I believe. "Journals" is the generic term for this.
[And she stops. Waiting for inevitable questions.]