Git Interview Questions

Q: What is the difference between Git and GitHub?

Git is a version control system that runs on your computer. GitHub is a website that hosts Git repositories online. Git = the tool; GitHub = the service.

Q: Explain the three areas of Git.

1. Working Directory — where you edit files
2. Staging Area — where you gather changes before committing
3. Repository — where commits are stored permanently

Files move: Working → git add → Staging → git commit → Repository

Q: What is the difference between git pull and git fetch?

git fetch downloads changes from GitHub without merging (safe, doesn’t affect your files). git pull downloads and merges changes (fetch + merge).

Q: What is git status used for?

It shows the current state of your repository — which branch you’re on, which files are modified, staged, or untracked. Run it constantly!

Q: How do you undo the last commit?

# Keep changes in staging (soft)
git reset --soft HEAD~1

# Keep changes in working directory (mixed)
git reset HEAD~1

# Delete changes completely (hard) ⚠️
git reset --hard HEAD~1

# Safe way (creates a new undo commit)
git revert HEAD

Q: What is a merge conflict and how do you resolve it?

A conflict happens when two branches change the same line of the same file. Git marks it with <<<<<<<, =======, and >>>>>>>. Fix by editing the file, removing markers, then git add and git commit.

Q: What is the difference between merge and rebase?

Merge creates a merge commit that ties two branches together (preserves history). Rebase replays commits on top of another branch (creates linear history). Never rebase shared branches.

Q: What is fast-forward merge?

When the target branch hasn’t moved since you branched off. Git just moves the pointer forward — no merge commit is created.

Q: What is a detached HEAD state?

When you check out a specific commit (not a branch), HEAD points directly to the commit. Any new commits are “detached” and will be lost when you switch branches. Fix by creating a branch: git checkout -b new-branch.

git checkout a1b2c3d    # detached HEAD
git checkout -b fix-bug # now on a real branch

Q: How do you add a remote repository?

git remote add origin https://github.com/user/repo.git

Q: What is the difference between git push and git push -u?

-u (or --set-upstream) sets the upstream tracking reference. After git push -u origin feature, you can just type git push in the future.

Q: What is a Pull Request?

A request to merge changes from one branch into another. It allows code review before merging. Standard way to collaborate on GitHub.

Q: What is the golden rule of rebase?

Never rebase commits that have been pushed to a shared branch. It rewrites history and causes problems for other developers.

Q: What is the difference between fork and branch?

A fork is a copy of the entire repo under your account (used when you don’t have write access). A branch is a line of development within the same repo (used by collaborators).

Q: How do you temporarily save work without committing?

git stash        # save work
git stash pop    # get it back
git stash list   # see all stashes

Q: What is git cherry-pick used for?

It applies a specific commit from one branch to your current branch. Useful when you only need one commit from another branch, not a full merge.

Q: What is git bisect?

A binary search tool that finds the exact commit that introduced a bug. You mark commits as “good” or “bad” and Git narrows it down.

git bisect start
git bisect bad       # current commit is broken
git bisect good v1.0 # v1.0 was working
# Git checks out the middle commit — test and repeat
git bisect reset

Q: What’s the difference between git reset and git revert?

git reset moves the branch pointer back (rewrites history — unsafe for shared branches). git revert creates a new commit that undoes changes (safe for shared branches).

Q: What would you put in a .gitignore?

• node_modules/ — dependencies
• .env — environment variables (secrets!)
• dist/ / build/ — compiled output
• .DS_Store / Thumbs.db — OS files
• *.log — log files