Merkle tree

Merkle tree is like a tree that has many smaller trees inside it. Imagine if you have some blocks, each with a special code, and you want to make sure that nobody changes the code without you knowing. You can put these blocks in a merkle tree!

First, you take two blocks and put them together in a special way. This is called hashing. It's like squishing the two blocks so that they become one small block, and you can't tell what the original blocks were by looking just at the small block. This small block is called a hash.

You do this with all your original blocks until you have a bunch of small hashes. These small hashes are the leaves of the merkle tree.

Then you start combining these small hashes into pairs and do the same thing again- hash them together to make another small hash. Keep doing this with the pairs of smaller hashes until you have only one hash left. This last hash is called the root hash, and it's very important.

If someone changes even one letter or number in one block, the hash will change and you will know that someone has tampered with it because the root hash would be different.

So the merkle tree is a way to help check that everything is as it should be, without having to check every single block individually. Just with the root hash, you can know if someone changed anything.