Imagine you have a coin, but instead of being a physical coin, it’s a chain of digital signatures.
Whenever you want to give the coin to someone else, you just add a new signature to the end of the chain.
The problem is, how can the person you give the coin to be sure that you didn’t make a copy of the coin and give it to someone else at the same time?
One solution is to have a trusted central authority, called a mint, that checks every transaction to make sure no one is double-spending.
But this means every transaction has to go through the mint, just like a bank.
Another solution is to make all transactions public so that everyone knows what’s happening.
Then everyone can agree on which transaction happened first, and that one will be the one that counts.
The payee needs to know that at the time of each transaction, the majority of the people involved agreed that it was the first received.
This way, there’s no need for a mint or a bank to check every transaction.