A Merkle Tree is a form of structure in Cryptography. In this structure, every “leaf node” is marked by the hash of a data block. In contrast, every “non-leaf node” is marked by the hash of its “child nodes”. This structure makes it possible to verify blockchains in an efficient and secure manner, because every change spreads upwards the tree. This ultimately means that you can verify something by simply looking at the top hash of the Merkle Tree.