# Module 03: Branching Basics

## Learning Objectives

In this module, you will:
- Understand what a branch is in Git
- Create new branches using `git branch` or `git switch -c`
- Switch between branches using `git switch`
- View all branches with `git branch`
- Understand that branches allow parallel development

## Challenge

### Setup

Run the setup script to create your challenge environment:

```powershell
.\setup.ps1
```

This will create a `challenge/` directory with a Git repository that has some initial commits on the main branch.

### Your Task

Your goal is to create a feature branch, make commits on it, and understand how branches work independently.

**Steps:**

1. Create a new branch called `feature-login`
2. Switch to the new branch
3. Create a new file `login.py` with some login functionality
4. Commit the new file to your feature branch
5. Make another change to `login.py` and commit it
6. Switch back to the main branch and observe that `login.py` doesn't exist there

**Suggested Approach:**

1. Navigate to the challenge directory: `cd challenge`
2. View existing branches: `git branch`
3. Create and switch to new branch: `git switch -c feature-login`
4. Create `login.py` with any content you like
5. Stage and commit: `git add login.py` and `git commit -m "Add login functionality"`
6. Modify `login.py`, then commit again
7. Switch back to main: `git switch main`
8. Run `ls` (or check your file explorer) and notice that `login.py` doesn't exist on main!
9. Switch back to feature-login: `git switch feature-login`
10. Run `ls` (or check your file explorer) again and see that `login.py` is back!

> **Important Notes:**
> - Use `git switch` to change branches
> - `git switch -c <name>` creates and switches in one command
> - Branches are independent - files in one branch don't affect another until you merge
> - You can switch between branches as many times as you want

## Key Concepts

- **Branch**: A lightweight movable pointer to a commit. Branches allow you to work on different features independently.
- **HEAD**: A pointer to the current branch you're working on. When you switch branches, HEAD moves.
- **main/master**: The default branch name in Git (main is the modern convention, master is older).
- **Feature Branch**: A branch created to develop a specific feature, separate from the main codebase.

## Useful Commands

```bash
git branch                   # List all branches (* shows current)
git branch <name>            # Create a new branch
git switch <branch>          # Switch to an existing branch
git switch -c <name>         # Create and switch to new branch
git switch -                 # Switch back to previous branch
git branch -d <name>         # Delete a branch (we won't use this yet)
```

## Verification

Once you've completed the challenge, verify your solution:

```powershell
.\verify.ps1
```

The verification script will check that you've created the branch, made commits, and that the branches are independent.

## Need to Start Over?

If you want to reset the challenge and start fresh:

```powershell
.\reset.ps1
```

This will remove the challenge directory and run the setup script again, giving you a clean slate.