Inside Git: How It Works and the Role of the .git Folder

How Git Works Internally

Most people use Git daily but don’t know what actually happens inside Git.
This short guide builds a clear mental model — no command memorization.

What Is the .git Folder?

• Created when you run git init

• This folder is the Git repository

• Stores:

  • History

  • Commits

  • Branches

  • Staging area

  • All Git data

👉 Delete .git = Git is gone

Inside the .git Folder (High Level)

Key parts only:

• objects/ → All data (files, commits)

• index → Staging area

• refs/ → Branch pointers

• HEAD → Current branch

Think of .git as Git’s internal database.

Git Stores Data Using Hashes

• Git tracks content, not files

• Uses SHA-1 hash

• Same content → same hash

• Small change → new hash

✅ Ensures data integrity
✅ Makes Git fast and reliable

Git Objects (Core Idea)

Git stores everything as objects.

1️⃣ Blob (File Content)

• Stores file data only

• No filename

• No folder info

2️⃣ Tree (Folder Structure)

• Stores filenames

• Connects files (blobs) & folders (trees)

3️⃣ Commit (Snapshot)

• Points to one tree

• Stores message, author, time

• Links to previous commit

Commit–Tree–Blob Relationship

Commit → Tree → Blob

• Commit = snapshot

• Tree = structure

• Blob = content

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How Git Tracks Changes

• Git does not store diffs

• Each commit is a snapshot

• Unchanged files reuse the same blob

💡 Saves space without duplicating data

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What Happens During git add

• Reads file content

• Creates a blob

• Stores it in .git/objects

• Updates the index (staging area)

👉 No commit yet

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What Happens During git commit

• Reads staging area

• Creates a tree

• Creates a commit object

• Moves branch pointer forward

👉 Snapshot is now permanent

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Branches & HEAD (One-Line Model)

• Branch = pointer to commit

• HEAD = pointer to branch

• Commits don’t move, pointers do

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Final Mental Model (Remember This)

• Git = snapshot system

• .git = real repository

• Everything = hash

• Commits → Trees → Blobs

• Branches = labels