Git and GitHub for Beginners: Essential Commands with Examples

Git is a version control system: it records every change to your code so you can go back, compare versions and work with a team without overwriting each other's work. GitHub (like GitLab or Bitbucket) hosts Git repositories online and adds pull requests, code review and CI/CD.

Every developer, tester and DevOps engineer uses Git daily.

One-time setup

git config --global user.name "Your Name"
git config --global user.email "you@example.com"
git config --global init.defaultBranch main

The three areas

Your first repository

mkdir my-project && cd my-project
git init
echo "# My Project" > README.md
git status
git add README.md
git commit -m "Add README"
git log --oneline

Write commit messages that say what changed and why, in the imperative: "Add login validation", not "changes".

Daily commands

git status                 # what changed?
git diff                   # exact line changes not yet staged
git add .                  # stage everything in this folder
git commit -m "Fix fee calculation for discounts"
git pull                   # get the latest from the remote
git push                   # send your commits to the remote

Branches: work without breaking main

git switch -c feature/login-page   # create and move to a new branch
# ...edit files, add, commit...
git push -u origin feature/login-page

Then open a Pull Request (PR) on GitHub. Teammates review the code, CI runs the tests, and when everything passes the branch is merged into main.

Keep branches small and short-lived. A PR with 200 changed lines gets a careful review; one with 3,000 lines gets a rubber stamp.

Merging and conflicts

git switch main
git pull
git merge feature/login-page

A merge conflict happens when two branches changed the same lines. Git marks the file:

<<<<<<< HEAD
const fee = 40000;
=======
const fee = 42000;
>>>>>>> feature/fee-update

Edit the file to keep the correct version, remove the markers, then:

git add pricing.js
git commit

Connect to GitHub

git remote add origin https://github.com/your-name/my-project.git
git push -u origin main

Undoing mistakes safely

Avoid git push --force on shared branches; it rewrites history for everyone. If you must, use --force-with-lease.

.gitignore: never commit secrets

Create a .gitignore file so passwords, keys and build output never enter the repository:

node_modules/
.env
.env.local
*.log
target/

If a secret is ever pushed, consider it leaked: rotate the key immediately, even after deleting the commit.

Interview questions

• `git fetch` vs `git pull`? fetch downloads changes without merging; pull = fetch + merge (or rebase).
• `merge` vs `rebase`? Merge keeps history as it happened with a merge commit; rebase replays your commits on top of the target for a linear history.
• `revert` vs `reset`? revert adds a new commit that undoes a change (safe for shared branches); reset moves the branch pointer and can discard history.

Next steps

Create a GitHub repository for your projects and practise the branch and PR flow daily. Then automate builds with Docker and CI/CD in the DevOps + AI course.