They track dollars.
When you get a US dollar that says "Where's George?" … you can type in it's serial number, say how you got it and where, and they'll tell you where it's been.
Very interesting.
This page came up in: AboutLogistics. We were imagining that in the future, people will carry packages across the country for each other, just because they can. Similar to WheresGeorge: You don't really have to do it; You can just do it, because you can. And it's somewhat educational to do so, and gives you a slightly different view of the world. That is: We see, in a very visceral way, that money moves. And also, that the online world isn't just a fairy world in it's own dimension– it is connected with the MaterialWorld?.
Define external redirect: MaterialWorld