Why is blockchain so secure?

Why is blockchain so secure?
Because it's like a giant spreadsheet that everyone has a copy of, and if you try to change one cell, everyone else's copy changes too.
But how does that make it secure?
Well, imagine you're trying to steal money from someone's bank account. You would need to change the balance in their account on every single copy of the spreadsheet. And if you tried to do that, everyone else would see that you had changed it, and they would know that you were trying to steal money.
So, blockchain is like a giant security camera that everyone can watch?
Exactly! And that's why it's so secure. It's impossible to change the data without everyone else knowing about it.
But what if I don't want everyone to see my transactions?
You can still use blockchain, but you can use a private blockchain. A private blockchain is like a regular blockchain, but only a select group of people have access to it.
So, blockchain is like a regular spreadsheet, but it's more secure and you can use it to keep your transactions private?
That's right! Blockchain is a really powerful technology, and it's only going to get more popular in the future.