docs: git objects

2020-12-23-git-objects.md

@@ -0,0 +1,21 @@
+# Git Objects
+
+Git Objects are Blob Object, Tree Object, Commit Object.
+
+All objects are stores at `.git/objects` with unique key (hash generated).
+
+**Blob Object** is file content.
+
+**Tree Object** is filename or directory.
+
+![Simple version of the Git data model](https://git-scm.com/book/en/v2/images/data-model-1.png)
+
+**Commit Object** contains top-level tree (snapshot at the time), parent commits, author and commit message.
+
+Branch is pointer, which point to commit we want.
+
+## References
+
+- [Git Internals - Git Objects](https://git-scm.com/book/en/v2/Git-Internals-Git-Objects)
+
+- [Commits are snapshots, not diffs](https://github.blog/2020-12-17-commits-are-snapshots-not-diffs/)