Git, one change at a time

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1. What is Git?

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Git is a free, open-source version control system. It keeps track of every change you make to your files, so you can always go back to an earlier version if something goes wrong.

It was created in 2005 by Linus Torvalds, the same person who created Linux! Git is the most popular version control system in the world.

Real-Life Analogy: The Time Machine!

Imagine you're writing a story. Every time you finish a chapter, you take a photo (snapshot) of the whole notebook. If you make a mistake later, you can look back at any photo to see what the story looked like before. Git does the same for your code and files!

Another Analogy: Save Points in Video Games!

In a video game, you save your progress at certain points. If your character dies, you restart from the last save. In Git, every time you "commit," you create a save point for your project!

Fun Fact!

The name "Git" is British slang for a silly person. Linus Torvalds joked that he names his projects after himself!

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2. Why Use Git?

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Git solves some very common problems that every developer faces:

Without Git (The Old Way)

People used to save files like: project_v1.zip, project_v2_final.zip, project_v2_final_REALLY_final.zip... It was messy and confusing!

With Git, you get:

⏪

Undo Mistakes
Go back to any previous version

👥

Teamwork
Many people can work on the same project

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History
See who changed what and when

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Branches
Try new ideas without breaking things

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3. Installing Git

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Git works on all operating systems. Here's how to install it:

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Linux (Ubuntu / Debian)

Open the Terminal and type:

$ sudo apt update
$ sudo apt install git
          

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Windows

Download from git-scm.com and run the installer. Keep all the default settings. This gives you "Git Bash" — a special terminal for Git.

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macOS

Open the Terminal and type:

$ git --version

If Git is not installed, macOS will ask you to install it.

Check if Git is Installed

Open your terminal and type git --version. If it shows a version number, you're ready!

$ git --version
git version 2.45.2
      

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4. First Time Setup

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Before using Git, you need to tell it who you are. This information appears in every commit you make.

# Set your name
$ git config --global user.name "Your Name"

# Set your email
$ git config --global user.email "your.email@example.com"

# Check your settings
$ git config --list
    

What does --global mean?

--global means this setting applies to ALL your projects on this computer. You only need to do this once!

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5. Git Workflow (The 3 Areas)

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Git has 3 important areas where your files live. Understanding these is the key to understanding Git!

The Three Areas of Git

📁 Working Directory

→

📋 Staging Area

→

💾 Repository

Your files on disk

Ready to commit

Saved history

git add →

git commit →

Analogy: Packing a Suitcase!

Working Directory = Your room with clothes everywhere.
Staging Area = The pile of clothes you've chosen to pack.
Repository = The locked suitcase, safely stored.

git add = picking clothes from your room → pile.
git commit = putting the pile into the suitcase and locking it.

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6. Essential Git Commands

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Starting a Project

# Create a new Git repository
$ git init

# Or download an existing project
$ git clone https://github.com/user/project.git
    

Making Changes

# Check which files have changed
$ git status

# Add a specific file to staging
$ git add filename.txt

# Add ALL changed files to staging
$ git add .

# Save (commit) with a message
$ git commit -m "Add new feature"
    

Viewing History

# See the list of all commits
$ git log

# See a short version of the log
$ git log --oneline

# See what changed in files
$ git diff
    

Good Commit Messages!

Always write clear commit messages that explain what you changed and why. Compare these:

❌ "fix stuff" — vague, unhelpful
✅ "Fix login button not working on mobile" — clear and useful!

Commit History Timeline

a3f2b1c

Add navigation menu

Ahmed — 2 hours ago

e7d4c2a

Fix homepage layout

Fatima — 5 hours ago

b1a9f3e

Create project structure

Ahmed — 1 day ago

f0e2d4b

Initial commit

Ahmed — 2 days ago

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7. Branches

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A branch is like a separate copy of your project where you can try new things without affecting the main code.

Analogy: A Tree!

Think of a tree. The trunk is your main project (called main branch). When you want to try something new, you grow a branch. If the branch grows well, you can merge it back to the trunk. If not, you can just cut it off!

# See all branches
$ git branch

# Create a new branch
$ git branch feature-navbar

# Switch to that branch
$ git checkout feature-navbar

# Create AND switch in one command
$ git checkout -b feature-navbar

# Go back to main branch
$ git checkout main

# Merge feature into main
$ git merge feature-navbar

# Delete a branch (after merging)
$ git branch -d feature-navbar
    

Merge Conflicts!

Sometimes two people change the same line in the same file. Git can't decide which version to keep — this is called a merge conflict. You need to manually choose which changes to keep, then commit the result.

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8. Remote Repositories & GitHub

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So far, everything has been on your computer (local). But what if you want to:

• Share your code with others?
• Have a backup in the cloud?
• Work on the project from another computer?

That's where remote repositories come in! Popular hosting services include GitHub, GitLab, and Codeberg (open source!).

Local ↔ Remote

💻 Your Computer
Local Repo

git push →

← git pull

☁️ GitHub
Remote Repo

# Connect your local repo to a remote one
$ git remote add origin https://github.com/user/project.git

# Upload (push) your commits to GitHub
$ git push -u origin main

# Download (pull) new changes from GitHub
$ git pull origin main

# Download a project from GitHub
$ git clone https://github.com/user/project.git
    

Open Source Alternatives!

While GitHub is the most popular, there are great open-source alternatives like Codeberg (codeberg.org) and Gitea that you can even host yourself!

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9. Try It Out! (Interactive Terminal)

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Type Git commands below and see what happens! Try commands like: git init, git status, git add, git commit, git log, git branch

Alin Li Git Terminal

Welcome to Alin Li Git Simulator! Type a git command and press Enter.

Try: git init, git status, git add, git commit, git log, git branch, git help

$

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10. Matching Game

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Drag each Git command to its correct description!

Commands

What It Does

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11. Flashcards

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Click each card to flip it and learn what each term means!

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Repository

Click to flip!

A folder tracked by Git. Contains all files, history, and branches of your project.

💾

Commit

Click to flip!

A snapshot of your project at a specific moment. Like a "save point" in a game.

🌿

Branch

Click to flip!

A separate version of your project where you can work without affecting the main code.

📋

Staging Area

Click to flip!

The "waiting room" where you prepare files before committing them.

🔀

Merge

Click to flip!

Combining changes from one branch into another. Like mixing two sets of changes together.

⬆️

Push

Click to flip!

Uploading your local commits to a remote repository (like GitHub).

⬇️

Pull

Click to flip!

Downloading new changes from a remote repository to your local computer.

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Clone

Click to flip!

Making a complete copy of a remote repository onto your local computer.

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12. Final Quiz

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Test your knowledge! Choose the correct answer for each question.

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13. Git Cheat Sheet

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Keep this handy! These are the most important Git commands you'll use:

git init

Start a new Git repository

git clone <url>

Copy a remote repository

git status

See what files have changed

git add <file>

Stage a file for commit

git add .

Stage ALL changed files

git commit -m "msg"

Save staged changes

git log

View commit history

git log --oneline

Short version of log

git diff

See what changed in files

git branch

List all branches

git branch <name>

Create a new branch

git checkout <branch>

Switch to a branch

git checkout -b <name>

Create + switch branch

git merge <branch>

Merge branch into current

git remote add origin <url>

Connect to remote repo

git push

Upload commits to remote

git pull

Download changes from remote

git stash

Temporarily save changes