$TREE What is a Merkle Tree in crypto?

A Merkle Tree, also known as a hash tree, is a hierarchical structure in which each leaf represents the hash of a transaction or a block of data. Each internal node (non-leaf) is the result of hashing the concatenation of the hashes of its children.

The process repeats from the leaves to the root, thus validating the integrity of all the data contained in the tree. The final root, called the Merkle Root, is included in the block header.