Excellent thread. I would like to see a few sentences at the end that also explain the initial creation of the supply. Whenever I try to explain Bitcoin along the lines of what is attempted here, I get asked about the origin of Bitcoins in circulation. Any suggestions?
Here is my attempt. I tried incorporating the new terminology, as well as a number of things about the security and workings of bitcoin in general.
"The recorders record the transactions to the public ledger, setting them in stone so to speak. This recording costs a lot of processing power, to prevent someone with malicious intent from adding fake pages to the ledger with their home computer. Or, for that matter, to prevent a government that wants to hurt bitcoin from adding fake pages to the ledger: the recorders' combined is larger than the 500 top supercomputers combined, which means it is impossible for
anyone to create fake pages.
As a compensation for the processing power, the recorders of the network currently get new coins. These coins didn't exist before, and slowly increase the supply of bitcoins available. The speed at which these new bitcoins are generated decreases over time. Currently there are about 7 million coins, but there will never be more than 21 million coins.
This reward for the recording serves both to distribute the new coins, and also to motivate people to be a recorder. Over time, the generation reward will go down. It is expected that at that point the transactions themselves will provide enough reward: Some of the transactions will cost a small fee, in the order of half a dollarcent. This fee is a reward to the recorders.
Having this small fee also prevents people from trying to harm bitcoin by sending lots and lots of small transactions, trying to clog the network. If they want to do that, it would actually cost them money, so the recorders would not care since they're compensated by small fees on the spam-transactions."
Note that I have taken some liberty in the explanation. The bit about "fake pages" is slightly different in reality, but I think it is more important to create an explanation that regular people from all backgrounds can understand. The difference between my explanation and the real explanation is small enough that they won't ever notice it, but it's much easier to explain. This still gives them a confidence in the security which is roughly equal to the real explanation.