Git Merge

git merge combines the work from one branch into another, bringing a completed feature or fix into your main codebase.

What Does git merge Do?

When you merge a branch, Git takes the commits from that branch and integrates them into the current branch. If both branches have progressed without conflicting changes, Git performs a fast-forward or automatic merge.

Merge a Branch into Your Current Branch

1. Switch to the branch you want to merge into (usually main):

git checkout main

2. Merge the feature branch:

git merge feature/user-login

Types of Merge

Fast-forward merge — if the target branch has no new commits since the feature branch was created, Git moves the pointer forward. No merge commit is created.

Three-way merge — if both branches have diverged, Git creates a new "merge commit" that ties the two histories together.

Create a Merge Commit Even on Fast-Forward

Useful for keeping a clear record that a feature branch was merged:

git merge --no-ff feature/user-login

Abort a Merge in Progress

If a merge goes wrong and you want to start over:

git merge --abort

After a Successful Merge

Push the updated branch to the remote:

git push origin main

tip

Merge into main only after code review. Use pull requests on GitHub rather than merging locally — this keeps an audit trail of who reviewed and approved the work.

Use --no-ff when merging feature branches to keep a visible history of when features landed.

Common Mistakes

Merging without committing local changes first — Git won't automatically commit your staged changes before merging. Commit or stash first.

Being on the wrong branch — always run git branch to confirm you're on the receiving branch before merging. Merging in the wrong direction can mix up histories.

Ignoring conflicts after a failed merge — if the merge stops with conflict markers in files, Git is waiting for you to resolve them. Don't leave conflicted files uncommitted. See the Resolving Merge Conflicts lesson.

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Next Steps: Resolving Merge Conflicts