Bitcoin works using something called a blockchain. Think of the blockchain like a special notebook where every Bitcoin transaction is written down. This notebook isn't kept in one place - thousands of computers around the world have a copy, so nobody can cheat or change the records!

Imagine if you and your friends were playing a game, and you needed to keep track of who had how many points. If only one person wrote down the scores, they might cheat! But what if everyone had their own copy of the score sheet, and everyone had to agree on any changes? That would make cheating almost impossible!

That's how the blockchain works. When someone sends Bitcoin to another person, this transaction is grouped together with other recent transactions into a "block." This block is then added to the chain of all previous blocks - that's why it's called a "blockchain!"

The really cool part is that once a block is added to the blockchain, it can't be changed or removed. It's there forever! This means no one can fake transactions or pretend they have more Bitcoin than they really do.

This system makes Bitcoin very secure and trustworthy, even though there's no bank or company in charge of it. It's all done by computers working together and following the same rules!