merkle-tree

The tree hashes its leaf node from bottom up till it reaches parent.

(https://en.wikipedia.org/wiki/Merkle_tree)

Merkle Root = H(H(v1||v2) || H(v3||v4))

                    |
     /------------------------------\
    /                                \

H(v1||v2) H(v3||v4) / \ /
/ \ /
v1 v2 v3 v4

(https://www.bsvblockchain.org/news/from-torrents-to-git-how-merkle-trees-protect-your-files)