Git Rebase vs. Merge: The Definitive Answer

The Oldest Debate in Software Engineering

You have been working on a feature branch for three days. Meanwhile, your teammates have merged five new pull requests into the main branch. Your branch is now horribly out of date. To push your code, you must incorporate their new changes. Do you use git merge main or git rebase main? This single question has sparked endless, heated debates among senior engineers.

The Git Merge: The Historical Truth

When you run git merge main, Git takes the latest commit on main, the latest commit on your feature branch, and creates a brand new "Merge Commit" that ties them together. It is a non-destructive operation.

Pros: It preserves the exact, chronological history of what actually happened. You can see precisely when the branches diverged and when they came back together.
Cons: If your team merges frequently, your git history chart will look like an incomprehensible spiderweb of crisscrossing lines. Bisecting bugs becomes a nightmare.

The Git Rebase: The Beautiful Lie

When you run git rebase main, Git does something magical and destructive. It temporarily sets your commits aside, updates your branch to exactly match main, and then "replays" your commits one-by-one on top of the new main. It literally rewrites history to make it look like you started working on your feature 5 minutes ago, after all your teammates were finished.

Pros: The git history is a perfectly straight, linear line. It is incredibly easy to read, easy to revert, and easy to run git bisect to find out exactly which commit introduced a bug.
Cons: Because you are rewriting history, you are changing the cryptographic hashes of your commits.

The Golden Rule of Rebasing

Because rebasing changes commit hashes, there is one absolute law you must obey: Never rebase commits that exist outside your local repository.

If you push your feature branch to GitHub, your coworker pulls it, and then you git rebase that branch locally and force-push it, you have just destroyed your coworker's local repository. Their git client will see two completely diverging, conflicting histories and they will be trapped in merge-conflict hell. You rebase your local, private branches to keep them clean before pushing. Once the code is public and shared, you strictly use merge.