What do Merkle Trees mean?
Each block in the bitcoin blockchain contains a summary of all the transactions in the block, using a Merkle tree. A Merkle tree, also known as a binary hash tree, is a data structure used for efficiently summarising and verifying the integrity of large sets of data.
Merkle trees are binary trees containing cryptographic hashes. The Merkle tree is useful because it allows users to verify a specific transaction without downloading the whole blockchain.
The term “tree” is used in computer science to describe a branching data structure, but these trees are usually displayed upside down with the “root” at the top and the “leaves” at the bottom of a diagram, as you will see in the examples that follow.