01 - Setup and Basics

#01 - Setup and Basics

##What is Git, and Why Should You Care?

Imagine you are writing a 50-page report in Word. You save it as report_final.docx. Then you make more changes: report_final_v2.docx. Then your manager edits it: report_final_v2_manager_edits.docx. After a week you have 10 files and no idea which is actually final.

Git solves this problem for code. Git is a version control system. It tracks every change you make to every file in your project — who changed it, when, and why. You can always go back to any previous version. You can work on different versions in parallel. And multiple people can collaborate without overwriting each other’s work.

Every company you will work at uses Git. It is as fundamental as knowing how to type.

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##Installing Git

Check if Git is already installed:

git --version

Expected output: git version 2.x.x

If you see “command not found”, install it:

• macOS: brew install git or download from https://git-scm.com/downloads
• Windows: Download from https://git-scm.com/downloads (includes Git Bash)
• Linux (Ubuntu/Debian): sudo apt-get install git

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##One-Time Configuration

Before you use Git, tell it who you are. Git stamps your name and email on every commit you make — so your teammates know who did what.

git config --global user.name "Priya Sharma"
git config --global user.email "[email protected]"
git config --global init.defaultBranch main

The --global flag means: apply this to ALL repositories on this machine. You only need to do this once per computer.

Verify your settings:

git config --list

Expected output (partial):

user.name=Priya Sharma
[email protected]
init.defaultBranch=main

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##Git’s Three-Area Model

This is the single most important thing to understand. Everything else in Git builds on this.

Think of it like a photographer’s workflow:

 Working Directory       Staging Area          Repository
 (your desk)             (camera roll)         (printed photo album)

 You write/edit          You select which       You save a permanent
 files here freely.      changes go into        snapshot (commit).
 Nothing is saved yet.   the next snapshot.     Can never be lost.

In Git commands:

Working Directory  git add  Staging Area  git commit  Repository

Working Directory: Your project folder. Edit files here freely.

Staging Area(also called the “index”): A collection zone. You pick exactly which changes to include before committing. This lets you make 5 edits but only commit 2 of them cleanly.

Repository: The permanent history, stored in the hidden .git folder. Every commit is a snapshot you can return to at any time.

###A real-world analogy

You are packing a suitcase for a trip. Your room (working directory) has clothes everywhere. You carefully choose what to pack (git add). When you zip the suitcase shut (git commit), that exact set of contents is locked in. Later you can open an old suitcase and see exactly what you packed on that day.

###The full picture (including remote)

Working Directory git add Staging Area git commit Local Repo git push Remote Repo
                                                                        git pull

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##Create Your First Repository

Let’s build this from scratch so you can feel every step.

mkdir my_first_repo
cd my_first_repo

Turn this folder into a Git repository:

git init

Expected output:

Initialized empty Git repository in /Users/you/my_first_repo/.git/

This creates a hidden .git folder. That folder IS your repository — all the history, all the snapshots, everything. Do not delete it.

Create a file:

touch README.md

Now ask Git what it sees:

git status

Expected output:

On branch main

No commits yet

Untracked files:
  (use "git add <file>..." to include in what will be committed)
        README.md

nothing added to commit but untracked files present

Git can see README.md but says “untracked”. This means: “I see this file exists, but I am not watching it yet. I will not track any changes you make to it.”

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##The Four File States

Every file in your project is always in one of these states:

State	What it means	How to move forward
Untracked	New file Git has never seen	git add <file>
Modified	Known file that has changed	git add <file>
Staged	Change ready to be committed	git commit -m "message"
Committed	Permanently saved in history	Nothing — you’re done!

Let’s see all four states in one sequence:

#--- UNTRACKED ---
git status
#Output: Untracked files: README.md

#Move to STAGED
git add README.md
git status
#Output: Changes to be committed:
#          new file: README.md

#Move to COMMITTED
git commit -m "Initial commit: add README"
git status
#Output: nothing to commit, working tree clean

#Back to MODIFIED — edit the file
echo "#My First Project" >> README.md
git status
#Output: Changes not staged for commit:
#          modified: README.md

#Stage the modification
git add README.md
git status
#Output: Changes to be committed:
#          modified: README.md

#Commit it
git commit -m "Add project title to README"
git status
#Output: nothing to commit, working tree clean

You just completed the core Git loop: edit stage commit. This is 80% of what you do with Git every single day.

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##git status is Your Best Friend

Run git status before and after every command until the workflow is automatic. It always tells you exactly where you are and hints at what to do next.

git status

How to read the output:

On branch main                           which branch you are on
Your branch is up to date with 'origin/main'.

Changes to be committed:                 STAGED (green in terminal)
  modified: index.html

Changes not staged for commit:           MODIFIED but not staged (red)
  modified: style.css

Untracked files:                         Git has never seen these
  script.js

nothing to commit, working tree clean    everything is committed, you are safe

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##Summary

Command	What it does
git init	Turn a folder into a Git repository
git status	See the current state of all files
git add <file>	Stage a file (move changes to staging area)
git add .	Stage ALL changed/new files at once
git commit -m "message"	Save staged changes as a permanent snapshot
git config --global ...	Set your name/email (once per machine)

Next: 02-local-workflow.md — Learn to commit like a professional