In Git, a history is a directed acyclic graph of snapshots and Git calls these snapshots "commit"s (which are immutable). All snapshots can be identified by their hash (hexadecimal characters, which are hard to remember) - so, Git’s solution to this problem is human-readable names for hashes, called "references". For example, the "master" reference usually points to the latest commit in the main branch of development.
Also,
In Git, a history is a directed acyclic graph of snapshots and Git calls these snapshots "commit"s (which are immutable). All snapshots can be identified by their hash (hexadecimal characters, which are hard to remember) - so, Git’s solution to this problem is human-readable names for hashes, called "references". For example, the "master" reference usually points to the latest commit in the main branch of development.
I think That value is known as SHA-value ...
correct me if I am wrong..
SHA-1 hash(a 40 character checksum hash).
git hash-object
will return that unique key.
Edit: A plan was formed to migrate git from SHA-1 to a stronger hash function. For more info check this link.