Version Control - Git and GitHub

📌 Remember: The goal of these notes is not to memorise every command. Focus on the mental model — how Git thinks, how history works, how teams collaborate. Once the model clicks, you can look up any command in seconds. Use these notes to build that understanding.

At the end of these notes there are two hands-on labs — one beginner, one advanced. Do not skip them. Reading about Git and actually using Git are very different things.

What You Will Learn

• What version control is and why every DevOps engineer depends on it daily
• The difference between Git and GitHub — they are not the same thing
• How to install and configure Git on any machine
• The three states of Git — the single most important concept to understand first
• The daily workflow every professional engineer repeats every working day
• How to write commit messages that actually help your team
• How to connect to GitHub with SSH so you never type a password again
• How to work with remote repositories — push, pull, fetch, and the difference between them
• How branches work and why every change goes on its own branch
• How to merge branches and resolve conflicts when they happen
• How to undo mistakes at every stage — staged, committed, pushed

Why This Matters

Every shell script, every Dockerfile, every Terraform module, every Kubernetes manifest, every pipeline config — all of it lives in version control. Nothing gets deployed from someone's laptop. Everything goes through the repository.

If you break something in production and there is no version control, you are guessing what changed. If two engineers edit the same file without version control, one of them loses their work. If you want to try a risky change without version control, you are afraid to even start.

Git removes all of that fear. It gives you a complete, permanent record of every change ever made — who made it, when, and why. You can travel back to any point in history. You can experiment freely knowing you can always undo. You can work with a hundred engineers on the same codebase without stepping on each other.

Git is not just a tool you use — it is the foundation that every other DevOps practice is built on top of.