# Git Merge vs Rebase: Differences, Examples, and Best Practices

When working with Git, you’ll often need to combine changes from one branch into another.

Two of the most common commands are **git merge** and **git rebase**. While both achieve a similar goal, they do it in very different ways. Every software engineer should understand the difference, along with the pros and cons of each approach.

## What Is Git Merge? (with Example)

`git merge` takes the history of two branches and creates a new **merge commit** (a “third” commit that ties the two histories together). This preserves the full record of how the branches diverged and then rejoined.

```bash
# Start on the main branch
git checkout main

# Merge feature branch into main
git merge your-feature-branch
```

### Merge History Example

```js
A---B---C (main)
      \
      D---E (your-feature-branch)
```

After merging:

```js
A---B---C-------M (main)
      \       /
      D---E (your-feature-branch)
```

_M is the new merge commit tying everything together._

✅ Advantages of git merge:

- Preserves complete history
- Useful for teams that want to see exactly when and how branches joined

❌ Disadvantages of git merge:

- Can lead to “messy” histories with lots of merge commits

## What Is Git Rebase? (with Example)

`git rebase` takes the commits from one branch and replays them on top of another. It does not create a merge commit. Instead, it rewrites commit history so it looks like you developed your work directly on top of the branch you rebased onto.

```bash
# Switch to feature branch
git checkout your-feature-branch

# Rebase feature branch onto main
git rebase main
```

### Rebase History Example

Before rebasing:

```js
A---B---C (main)
      \
      D---E (your-feature-branch)
```

After rebasing:

```js
A---B---C---D'---E' (your-feature-branch)
```

_`D` and `E` are new commits replayed on top of `C`._

Here’s what actually happened:

- Git created new commits with the same changes as `D` and `E`, but their parent is now `C`.
- Your **feature branch** pointer moved to `E`.
- The **main branch** is still at `C`. It hasn’t changed.

So although the history now looks like a straight line, main hasn’t advanced. Your branch is just “rebased on top of main.”

When you merge it back, Git can often do a **fast-forward merge** (moving main forward with no extra commit). **If you want to see what that looks like, check the Fast-Forward Merge section below.**

✅ Good for:

- Cleaner, linear history
- Easier to follow when reviewing logs

❌ Downside:

- Rewrites history (can be risky on shared branches)

## Fast-Forward Merge (After Rebase)

After rebasing, merging your feature branch back into main is often just a fast-forward:

```bash
git checkout main
git merge your-feature-branch   # fast-forward merge
```

Result:

```js
A---B---C---D'---E' (main, your-feature-branch)
```

Here, Git simply moves the `main` pointer forward.  
No merge commit is created — the history looks like your work was always built directly on top of main.

## Git Merge vs Rebase: Which Should You Use?

- Use merge if you value preserving the true history of your project.
- Use rebase if you want a clean, linear history that’s easy to read.

In practice, many teams use rebase for local cleanup (before pushing) and merge when integrating shared work.

## Final Thoughts

Both `git merge` and `git rebase` are powerful tools. The choice comes down to whether you prioritize **historical accuracy** (merge) or **clean, readable history** (rebase).

Understanding when to use each will make your Git workflow smoother, whether you’re working solo or collaborating with a team.