We have our chained blocks where we write the transactions, we have the miners who write on that blockchain and get new coins into the system, and we have the keys and addresses for our players to receive coins.
I don’t know if you noticed, but we’re missing an important actor here. Who’s gonna be in charge of keeping all the copies of that shared list? Because if a bunch of people with copies agree on cheating, they could write some extra money for them by modifying their copies and claim they’re the “real” list copies. The problem we’re encountering is sometimes referred to as the Bizantine Generals’ Problem.
To avoid that we need more people having copies. How many? As many as possible, so many as to render it very very difficult for more than half of them to agree on cheating. Because the players of the game will check the blockchain copies, and if the majority of the copies looks identical, will take that as the true list. That’s why if more than 51% of the copies are identical, everything works even if the other 49% aren’t. We as players will just assume they’re wrong and discard them.
In the case of our Monero game, to have as many people with copies as possible, anybody is able to have one for free. It’s public after all. And since our money is digital, that copy of the list is a digital file as well, stored on a computer connected to the internet. We’ll call those computers nodes.