Merkle Tree

Merkle Trees

Merkle trees are data structure trees where each non-leaf node is a hash of its respective child node. The leaf nodes are the lowest tier of nodes in the tree. It was named after Ralph Merkle who patented this concept in 1979.

Merkle Trees help in efficient and secure verification of large data structures. These are a fundamental component of blockchains because in the case of blockchains, potentially boundless data sets are used. The implementation of Merkle trees in blockchains has multiple effects. It allows them to scale and provide the hash-based architecture for them to maintain data integrity. Cryptographic hash functions are the underlying technology that allows for Merkle trees to work.

It is easier to understand the concept using the above pictorial view. Notice the non-leaf nodes or branches are represented by hashes of their respective children. The pictorial example is the most common and simple form of a Merkle Tree known as a Binary Merkle Tree. The top hash of the tree is known as the root hash. So, we can also understand Merkle Tree as a data structure which can take ‘n’ number of elements and represent it with a single hash.

How is this convenient for data verification?
The tree structure allows efficient mapping of an arbitrarily large amount of data. And helps in easy identification of where changes in data occur. This is also the underlying basis of Merkle proofs. It can be verified that the data chunk is consistent with the root hash by checking only a small subset of the hashes rather than the entire data set.

Source: https://blockonomi.com/merkle-tree/