Git Merge vs Rebase: What Is the Difference?

Blog / Git Merge vs Rebase: What Is the Difference?

What exactly is the difference between a Git merge and a Git rebase? And when should you use each one?

The Diverged Branches Problem

Imagine this common scenario:

You branch off the main branch to build a new feature.
You make progress and create new commits.
Meanwhile, the main branch gets new commits from other people.

Now the two branches have diverged. Your feature branch lacks the new updates from main, and main lacks your new feature.So how can we solve this? Both merge and rebase bring them back together, but in different ways.

How a Git Merge Works

A Git merge takes the two diverged branches and ties them together. It keeps every single commit from both branches exactly as they were.Then it adds one brand new commit called a merge commit.This new commit has two parent commits: the latest commit on main and the latest commit on your feature branch. Together they represent the exact moment the work joined back together.

A merge commit with two parents, the latest commit on main and the latest commit on the feature branch

The history keeps its branch shape, showing exactly when the work joined.However, heavily merged repositories can become hard to read. This is where Git rebase comes in.

How a Git Rebase Works

A Git rebase literally changes the history of your repository.It lifts your feature commits off their original starting point. Then it replays them one by one on top of the latest main branch.Because these commits are applied in a new location, Git generates a completely new ID for each replayed commit.

After a rebase, E and F are replayed on top of main as E′ and F′, the same changes with new IDs

The history is rewritten into one straight line. This completely removes the branch shape.

When to Use Merge

Since both git merge and git rebase bring branches together, you must choose carefully.You should use merge when you are bringing a finished feature into a shared main branch. This preserves the true record of exactly when work came together.Squash mergeSometimes a feature branch has too many tiny, messy commits. In that case, you can use a squash merge. It bundles all of the branch's commits into a single commit on main.

When to Use Rebase

You should use rebase when you are tidying up your own local feature branch. It is highly useful right before you open a pull request.By rebasing your feature branch on top of the latest main, you bring in all the newest updates.This ensures your history reads as one clean, straight line. It makes the final review much easier for your team to follow.

The Golden Rule of Rebasing

Because rebasing rewrites history, there is a strict rule you must follow.Never rebase a branch that other people are using.A rebase creates entirely new commit IDs. If you rebase a shared branch, your teammates will have the old commit IDs on their computers.Their local copies will no longer match your updated branch. This causes huge conflicts that are very difficult to fix.

Rebasing a shared branch leaves a teammate with the old commits E and F, which no longer match E′ and F′

Recap

	Git Merge	Git Rebase
Commits	Preserves original commits	Rewrites with new commit IDs
History shape	Keeps branch structure	Creates one straight line
Best used for	Shared branches	Local feature branches

Merge keeps your exact history and adds a merge commit. It is the safe choice for shared branches.Rebase replays your work on top of the latest changes to create a straight line. It is perfect for cleaning up local work.Just remember to never use it on a branch someone else is using.

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