Until now, I learned:

• How to create branches

• How to switch branches

• How to commit

• How to push to GitHub

But today I learned something very important:

👉 How branches come back together
👉 How to safely switch work
👉 How to move commits
👉 How to copy specific commits

These are real-world Git skills.

Let’s understand everything step by step in very easy language.

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🌿 Task 1 – Git Merge (How Branches Join Together)

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🧠 What is Merge?

When we finish working on a feature branch,
we need to bring that feature into main.

That process is called:

MERGE

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✅ Step 1: Create feature-login branch

git switch main
git switch -c feature-login

Explanation:

• git switch main → Go to main branch

• -c feature-login → Create a new branch from current position

Now add some commits:

echo "Login Page" > login.txt
git add login.txt
git commit -m "Added login page"

echo "Login validation" >> login.txt
git add login.txt
git commit -m "Added login validation"

Now feature-login has 2 commits.

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✅ Step 2: Merge into main

git switch main
git merge feature-login

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🧐 What happened?

If no new commit was added to main after creating the branch,

Git performs:

⚡ Fast-Forward Merge

What is Fast-Forward Merge?

It means:

Main simply moves forward to match feature branch.

Before:

A --- B (main)
        \
         C --- D (feature-login)

After merge:

A --- B --- C --- D (main)

No extra merge commit created.

Git just moved the pointer forward.

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🔁 Now Let’s See Merge Commit

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✅ Create feature-signup

git switch -c feature-signup

Add commit:

echo "Signup Page" > signup.txt
git add signup.txt
git commit -m "Added signup page"

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✅ Add commit to main before merging

git switch main
echo "Hotfix" > hotfix.txt
git add hotfix.txt
git commit -m "Hotfix commit"

Now main has a new commit.

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✅ Now merge feature-signup

git merge feature-signup

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🧐 What happened?

Now Git creates:

🔀 Merge Commit

Because:

• Main moved forward

• Feature branch also has commits

• History is different

Git creates a new commit that joins both histories.

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❗ What is a Merge Conflict?

A merge conflict happens when:

Both branches change the same line in the same file.

Example:

On main:

Hello World

On feature:

Hello DevOps

When merging, Git gets confused.

You will see:

<<<<<<< HEAD
Hello World
=======
Hello DevOps
>>>>>>> feature-branch

You must manually edit and decide which version to keep.

After fixing:

git add file.txt
git commit

Conflict resolved.

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🌊 Task 2 – Git Rebase (Clean History Method)

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🧠 What is Rebase?

Rebase means:

Move your branch on top of another branch.

Instead of combining histories like merge,
rebase rewrites history to make it straight.

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✅ Create feature-dashboard

git switch main
git switch -c feature-dashboard

Add commits:

echo "Dashboard UI" > dashboard.txt
git add dashboard.txt
git commit -m "Added dashboard UI"

echo "Dashboard API" >> dashboard.txt
git add dashboard.txt
git commit -m "Added dashboard API"

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✅ Move main forward

git switch main
echo "Security patch" > security.txt
git add security.txt
git commit -m "Security patch"

Now main moved ahead.

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✅ Rebase feature-dashboard onto main

git switch feature-dashboard
git rebase main

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🧐 What does rebase do?

It takes your commits and:

• Removes them temporarily

• Moves branch to latest main

• Reapplies your commits on top

Before:

A --- B --- E (main)
       \
        C --- D (feature-dashboard)

After rebase:

A --- B --- E --- C' --- D'

It looks clean and straight.

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❗ Why should you NEVER rebase pushed commits?

Because:

Rebase rewrites history.

If someone already downloaded those commits,
you will break their repository.

Golden rule:

Never rebase shared commits.

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🆚 Rebase vs Merge

Use Merge:

• In team projects

• For shared branches

Use Rebase:

• For personal branches

• To clean history before pushing

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🧹 Task 3 – Squash Commit vs Regular Merge

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✅ Create feature-profile

git switch -c feature-profile

Make small commits:

git commit -m "Added profile page"
git commit -m "Fixed typo"
git commit -m "Formatting fix"
git commit -m "Minor improvement"

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✅ Squash merge

git switch main
git merge --squash feature-profile
git commit -m "Added profile feature"

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🧐 What happened?

Instead of 4 commits,
main gets only 1 commit.

That is squash merge.

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📌 What is Squash Merge?

It combines all commits into one single commit.

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🔁 Regular Merge

git merge feature-settings

Regular merge keeps all commits separate.

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🎯 When to use squash?

Use squash when:

• Many small messy commits

• Want clean main branch

Trade-off:

• You lose detailed commit history

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📦 Task 4 – Git Stash (Temporary Save)

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🧠 What is Stash?

Stash means:

Temporarily save unfinished work.

Imagine:

You are coding.
Suddenly urgent bug appears.
You must switch branch.

But you haven't committed yet.

Use stash.

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✅ Make uncommitted changes

echo "Work in progress" >> login.txt

Try switching:

git switch main

Git may stop you.

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✅ Save using stash

git stash

Now your changes are saved safely.

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✅ Bring changes back

git stash pop

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🆚 Difference: pop vs apply

pop	apply
Applies and deletes stash	Applies but keeps stash

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📌 When to use stash?

• Urgent bug fix

• Switching tasks temporarily

• Not ready to commit

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🍒 Task 5 – Cherry Pick

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🧠 What is Cherry Pick?

Cherry pick means:

Copy one specific commit from another branch.

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✅ Create feature-hotfix

git switch -c feature-hotfix

Make 3 commits.

Check commit hashes:

git log --oneline

Example:

a1b2c3 Fix typo
d4e5f6 Security fix
g7h8i9 UI update

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✅ Cherry pick only second commit

git switch main
git cherry-pick d4e5f6

Now only that commit is added to main.

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📌 When to use cherry-pick?

• Urgent production fix

• Apply one bug fix to another branch

• Hotfix scenario

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⚠ What can go wrong?

• Duplicate commits

• Merge conflicts

• Messy history