The Bitcoin FAQ - 1: Ledger
(Not the company)
In this series of articles, I try to answer a question related to Bitcoin with the analogy or explanation I found fit the best.
Question 1: Bitcoin is using a public ledger. What is it?
To me, the best analogy or even illustration of the concept is the poker game.
Imagine you are having a poker night with some friends.
That night, maybe you forgot to bring your poker coins.
So one of you is designated to write down on a piece of paper the results of every match.
The thing is after ten matches, for anybody, it's hard to remember what happened.
So when you check the notes from your friend at the end of the night, you can't tell if your friend cheated or maybe just made a mistake on any particular match.
It is where the public ledger comes to play.
Now imagine instead of having only one friend keeping the books, all of your friends, including you, keep a copy of that ledger.
At every match, all of you write down the results in your ledger.
You understand now that it's going to be harder to make a mistake as you can compare with your friends at any time!
It is what the bitcoin public distributed ledger is all about. Everybody gets a copy so that you can verify and double-check with everybody your copy.