Key Takeaways

1. Git is a Content-Addressable Filesystem: It stores data as snapshots, addressed by SHA-1 hash.
2. The Object Model: History is built from Blobs (files), Trees (directories), Commits (snapshots), and Tags.
3. The Three Trees: Data moves from Working Directory → Staging Area (Index) → Repository.
4. The Index: A binary cache of the working directory that prepares the next commit.
5. The DAG: Commits form a Directed Acyclic Graph. History is immutable because parent hashes are baked into child commits.

Interactive Flashcards

Test your knowledge by clicking the cards to flip them.

What are the 4 main Git Objects?

Blob, Tree, Commit, Tag

Where is the Staging Area stored?

It is a binary file located at .git/index.

Why is Git history immutable?

Because the parent's SHA-1 hash is part of the child commit's data. Changing a parent changes its hash, breaking the chain.

Cheat Sheet

Command	Action	Tree Movement
git add <file>	Stages a file	Working Dir → Index
git commit	Saves a snapshot	Index → Repository
git checkout <branch>	Updates files to match commit	Repository → Index → Working Dir
git status	Shows differences	Compares Working Dir vs Index vs HEAD
cat .git/HEAD	Shows current branch ref	N/A
git cat-file -p <hash>	Prints object content	N/A

Next Steps

Now that you understand the Architecture, you are ready to learn how to manipulate it.

Proceed to Module 2: Branching and Merging to learn about recursive merge strategies, rebase vs merge, and conflict resolution.

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