The baseline data structures for Fossil and Git are the same, modulo
formatting details. Both systems manage a
[https://en.wikipedia.org/wiki/Directed_acyclic_graph | directed acyclic
graph] (DAG) of [https://en.wikipedia.org/wiki/Merkle_tree | Merkle
tree] / [./blockchain.md | block chain] structured check-in objects.
Check-ins are identified by a cryptographic hash of the check-in
contents, and each check-in refers to its parent via <i>its</i> hash.

The difference is that Git stores its objects as individual files in the
<tt>.git</tt> folder or compressed into bespoke
[https://git-scm.com/book/en/v2/Git-Internals-Packfiles|pack-files],
whereas Fossil stores its objects in a [https://www.sqlite.org/|SQLite]
database file using a hybrid NoSQL/relational data model of the check-in
history. Git's data storage system is an ad-hoc pile-of-files key/value