Git, GitHub & GitHub Copilot — From Zero to Mastery

A complete, plain-language tutorial that takes you from never having used version control to understanding the deepest internals of Git, GitHub, and GitHub Copilot — including how Copilot’s skills, custom instructions, context window, and memory actually work under the hood.

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Who this is for

• Complete beginners who have never typed git in their life.
• Working developers who use Git daily but never understood what lives inside the .git folder.
• Anyone using GitHub Copilot who wants to know how it decides which skill to load, how it manages context, and how its memory works.

You do not need any prior knowledge. Every term is explained the first time it appears, and there is a full glossary at the end.

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How this tutorial is structured

The tutorial is split into 15 modules, each in its own file inside the modules/ folder. They are ordered so each builds on the last, but the headings are self-contained enough that you can jump around once you know the basics.

The journey has three big parts:

1. Part A — Git foundations (Modules 1–5): what version control is, installing Git, your first repository, and the single most important chapter: what Git actually writes inside the .git folder.
2. Part B — GitHub & collaboration (Modules 6–9): remotes, pull requests, issues, undoing mistakes, and advanced day-to-day Git.
3. Part C — GitHub Copilot internals (Modules 10–14): Copilot itself, custom instructions, how skills work and how Copilot decides which skill file to load, how it manages context and memory, and a mastery workflow that ties everything together.
4. Part D — Safety & security (Module 15): keeping your code, credentials, and AI workflow safe across Git, GitHub, and Copilot.

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The modules

#	Module	What you’ll learn
01	What Version Control Really Is	The problem Git solves, snapshots vs. diffs, why Git is “distributed”
02	Installing & Configuring Git	Install on every OS, identity, SSH keys, the global config
03	Your First Repository	init, the three areas, add, commit, status, log, diff
04	Inside the .git Folder	Every file and folder Git creates, and what each one does
05	Branching, Merging & Rebasing	Branches as pointers, merge vs. rebase, conflicts
06	Remotes & GitHub	clone, push, pull, fetch, what GitHub adds on top of Git
07	Collaboration: PRs, Issues & Reviews	Forks, pull requests, code review, GitHub Actions basics
08	Undoing Things & Recovery	reset, revert, restore, the reflog safety net
09	Advanced Git	Stash, cherry-pick, bisect, hooks, submodules, .gitignore
10	Meet GitHub Copilot	Completions vs. chat vs. agent mode, plans, where it runs
11	Customizing Copilot: Instructions & Prompt Files	The 5 customization layers and how they merge
12	Copilot Skills: How They Work	SKILL.md, frontmatter, and how Copilot decides which skill to load
13	Context & Memory	The context window, compaction, and Copilot’s memory system
14	Mastery: Putting It All Together	A professional workflow combining Git + Copilot
15	Safety & Security	Secrets, signing, branch protection, scanning, and Copilot security

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How to use it

• Read in order if you’re new. Each module ends with a short “Try it yourself” section — actually run the commands. Reading Git without typing it is like reading about swimming.
• Use the glossary whenever a word feels unfamiliar. Terms are linked back to where they’re explained.
• Commands are shown in code blocks. Lines starting with # are comments (you don’t type them). Output is shown when it helps.

A note on accuracy: Git’s behavior is extremely stable and rarely changes. GitHub Copilot, by contrast, evolves quickly — the file names, frontmatter fields, and memory behavior described in Part C reflect how Copilot works as of mid-2026. Always cross-check the official Copilot docs for the newest details. Source links are included at the bottom of the Copilot modules.

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A 60-second mental model before you start

Three ideas carry you through the whole tutorial:

1. Git is a database of snapshots. Every time you “commit,” Git takes a photograph of your whole project and stores it forever, addressed by a unique fingerprint (a hash). Nothing is ever really lost.
2. GitHub is a place to host that database and collaborate around it. Git works perfectly offline and alone; GitHub adds the social layer — sharing, reviewing, automating.
3. Copilot is an AI teammate that reads your code and your instructions. It has a limited “working memory” (the context window), it pulls in extra knowledge on demand (skills), and it keeps notes between sessions (memory). Understanding those three mechanisms is what separates casual users from power users.

Turn to Module 01 when you’re ready.