Git & GitHub: Complete Guide

A comprehensive guide to Git and GitHub commands, features, and best practices with detailed examples.

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Table of Contents

1. Introduction
2. Installation & Setup
3. Basic Git Commands
4. Branching
5. Merging & Rebasing
6. Remote Repositories
7. GitHub Features
8. Advanced Git Workflows
9. Common Workflows
10. Best Practices

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Introduction

Git is a distributed version control system that helps track code changes and collaborate with others.

GitHub is a cloud-based hosting service for Git repositories with additional collaboration features.

Key Benefits

• Track changes over time
• Collaborate with multiple developers
• Revert to previous versions easily
• Maintain code history
• Work on features independently using branches

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Installation & Setup

Install Git

Windows

# Download from https://git-scm.com/download/win
# Or use package manager
choco install git
# Or using winget
winget install Git.Git

macOS

# Using Homebrew
brew install git

Linux

# Ubuntu/Debian
sudo apt-get install git

# Fedora
sudo dnf install git

Initial Configuration

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

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

# View all configuration
git config --list

# Set configuration for specific repository (local)
git config user.name "Your Name"
git config user.email "your.email@example.com"

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Basic Git Commands

Initialize a Repository

# Create a new Git repository
git init

# Clone an existing repository
git clone https://github.com/username/repository.git

# Clone to a specific directory
git clone https://github.com/username/repository.git my-folder

Example:

git clone https://github.com/torvalds/linux.git
# Downloads the Linux repository to your machine

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Check Repository Status

# View status of working directory
git status

# View short status
git status -s

Example Output:

On branch main
Your branch is up to date with 'origin/main'.

Changes not staged for commit:
  (use "git add <file>..." to stage for commit)
        modified:   index.js

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

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Staging Changes

# Stage a specific file
git add filename.js

# Stage all changes
git add .

# Stage all changes in current directory
git add .

# Stage specific file type
git add *.js

# Stage with interactive prompt
git add -i

# Stage part of a file (hunk)
git add -p filename.js

Example:

# After modifying index.js and app.js
git add index.js       # Stage only index.js
git add .              # Stage both index.js and app.js
git add *.js           # Stage all JavaScript files

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Commit Changes

# Commit with message
git commit -m "Add new feature"

# Commit with detailed message
git commit -m "Add new feature" -m "This feature implements user authentication"

# Stage and commit in one command (tracked files only)
git commit -am "Fix bug in login"

# Amend last commit (add changes to previous commit)
git commit --amend --no-edit

# Amend last commit and change message
git commit --amend -m "New commit message"

Example:

git add .
git commit -m "Implement user registration"
# Creates a commit with all staged changes

git commit --amend -m "Implement user registration and email verification"
# Updates the message of the last commit

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View History

# View commit history
git log

# View last N commits
git log -n 5

# View one-line commit history
git log --oneline

# View commit history with graph
git log --oneline --graph --all

# View commits by specific author
git log --author="Author Name"

# View commits after specific date
git log --since="2024-01-01"

# View commits before specific date
git log --until="2024-12-31"

# View commits with file changes
git log --stat

# View commits with detailed changes
git log -p

# Search for commits by message
git log --grep="feature"

Example:

git log --oneline --graph --all -n 10
# Shows last 10 commits in one-line format with branch visualization

git log --author="John Doe" --since="2024-01-01"
# Shows commits by John Doe from January 2024 onwards

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View Differences

# Show changes in working directory
git diff

# Show changes between staging area and repository
git diff --staged

# Show differences between two commits
git diff commit1 commit2

# Show differences in specific file
git diff filename.js

# Show differences between branches
git diff branch1 branch2

Example:

git diff
# Shows all uncommitted changes

git diff --staged
# Shows what will be committed

git diff main feature-branch
# Shows differences between main and feature-branch

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Branching

Create & Switch Branches

# Create a new branch
git branch branch-name

# Create and switch to new branch
git checkout -b branch-name

# Create and switch (modern syntax)
git switch -c branch-name

# Switch to existing branch
git checkout branch-name

# Switch branches (modern syntax)
git switch branch-name

# List all branches (local)
git branch

# List all branches (local and remote)
git branch -a

# List branches with last commit info
git branch -v

# Delete a branch
git branch -d branch-name

# Force delete a branch
git branch -D branch-name

# Rename a branch
git branch -m old-name new-name

Example:

# Create and work on a new feature
git checkout -b feature/user-authentication

# Make changes and commit
echo "login code" > auth.js
git add auth.js
git commit -m "Add authentication module"

# List all branches
git branch
# Output:
#   feature/user-authentication
# * main

# Switch back to main
git checkout main

# Delete the feature branch
git branch -d feature/user-authentication

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Branch Naming Conventions

# Feature branch
git checkout -b feature/user-login

# Bug fix branch
git checkout -b bugfix/navbar-alignment

# Release branch
git checkout -b release/v1.0.0

# Hotfix branch
git checkout -b hotfix/critical-security-patch

# Development branch
git checkout -b develop

# Experimentation branch
git checkout -b experiment/new-ui-design

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Merging & Rebasing

Merging Branches

# Merge a branch into current branch
git merge branch-name

# Merge with commit message
git merge branch-name -m "Merge feature branch"

# Abort an ongoing merge
git merge --abort

# Squash commits before merging
git merge --squash branch-name

# Fast-forward merge only
git merge --ff-only branch-name

# No fast-forward merge
git merge --no-ff branch-name

Example:

# Create feature and make changes
git checkout -b feature/dark-mode
echo "dark mode styles" > styles.css
git add styles.css
git commit -m "Add dark mode"

# Merge back to main
git checkout main
git merge feature/dark-mode

# Output:
# Updating abc1234..def5678
# Fast-forward
#  styles.css | 1 +
#  1 file changed, 1 insertion(+)

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Rebasing

# Rebase current branch onto another branch
git rebase branch-name

# Interactive rebase (last N commits)
git rebase -i HEAD~3

# Continue after resolving conflicts
git rebase --continue

# Abort rebase
git rebase --abort

# Rebase and keep merge commits
git rebase --preserve-merges branch-name

Example:

# On feature branch
git rebase main
# Replays feature branch commits on top of main

# Interactive rebase of last 3 commits
git rebase -i HEAD~3
# Opens editor to reorder, squash, or edit commits

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Remote Repositories

Adding & Removing Remotes

# View remote repositories
git remote

# View remote URLs
git remote -v

# Add a remote repository
git remote add origin https://github.com/username/repo.git

# Add a secondary remote
git remote add upstream https://github.com/original-owner/repo.git

# Remove a remote
git remote remove origin

# Rename a remote
git remote rename origin upstream

# Change remote URL
git remote set-url origin https://github.com/username/new-repo.git

# View remote information
git remote show origin

Example:

git remote add origin https://github.com/john/my-project.git
git remote add upstream https://github.com/original/my-project.git

git remote -v
# Output:
# origin    https://github.com/john/my-project.git (fetch)
# origin    https://github.com/john/my-project.git (push)
# upstream  https://github.com/original/my-project.git (fetch)
# upstream  https://github.com/original/my-project.git (push)

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Push & Pull

# Push commits to remote branch
git push origin branch-name

# Push all commits
git push

# Push to remote and set upstream
git push -u origin branch-name

# Push tags
git push origin --tags

# Push specific tag
git push origin tag-name

# Delete remote branch
git push origin --delete branch-name

# Pull changes from remote
git pull

# Pull from specific remote and branch
git pull origin main

# Fetch without merging
git fetch

# Fetch from all remotes
git fetch --all

Example:

# Create local feature branch
git checkout -b feature/notifications

# Make changes
echo "notification system" > notify.js
git add notify.js
git commit -m "Add notification system"

# Push to remote and set upstream
git push -u origin feature/notifications

# Later, pull updates from remote
git pull origin feature/notifications

# Delete remote branch after merging
git push origin --delete feature/notifications

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GitHub Features

Pull Requests (PR)

Pull Requests allow code review and discussion before merging.

Workflow:

1. Create a feature branch
2. Push to GitHub
3. Create Pull Request
4. Request reviewers
5. Address feedback
6. Merge to main branch

Example:

# Create and push feature branch
git checkout -b feature/payment-gateway
echo "payment code" > payment.js
git add payment.js
git commit -m "Implement Stripe integration"
git push -u origin feature/payment-gateway

# Now create PR on GitHub website
# Go to: https://github.com/username/repo/pulls
# Click "New Pull Request"
# Select main branch as base
# Add title and description
# Request reviewers
# Submit PR

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Issues

Issues track bugs, feature requests, and tasks.

Create Issue via GitHub UI:

• Navigate to repository
• Click "Issues"
• Click "New Issue"
• Add title and description
• Assign labels, assignees, milestones
• Click "Submit new issue"

Reference in Commits:

# Reference issue in commit message
git commit -m "Fix login bug #123"

# Close issue automatically
git commit -m "Fix login bug - closes #123"

# Reference pull request
git commit -m "Implements feature #456"

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Labels

Organize issues and PRs with labels.

Common Labels:

• bug - Something isn't working
• enhancement - New feature or request
• documentation - Improvements or additions to documentation
• good first issue - Good for newcomers
• help wanted - Extra attention is needed
• priority-high - Urgent
• priority-low - Can wait
• testing - Needs testing

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Milestones

Group issues and PRs into release versions.

Usage:

• Create milestone on GitHub
• Add issues to milestone
• Track progress toward release
• Automate workflows based on milestones

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Projects

Organize work with kanban-style boards.

Features:

• Create custom columns
• Drag and drop cards
• Automate transitions
• Track multiple repositories

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Discussions

Community conversations separate from issues.

Use Cases:

• Q&A
• Announcements
• General discussions
• Polls and surveys

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Advanced Git Workflows

Stashing Changes

Save work without committing.

# Stash current changes
git stash

# Stash with description
git stash save "description"

# List all stashes
git stash list

# Apply latest stash
git stash pop

# Apply specific stash
git stash apply stash@{0}

# Keep stash after applying
git stash apply stash@{0}

# Delete a stash
git stash drop stash@{0}

# Delete all stashes
git stash clear

# Show stash contents
git stash show stash@{0}

Example:

# Working on feature but need to switch branches
git stash
# Stash has been saved to stash@{0}

# Switch and work on another branch
git checkout hotfix/critical-bug

# After fixing, return to original work
git checkout feature/new-feature
git stash pop

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Cherry-Picking

Apply specific commits from one branch to another.

# Cherry-pick a commit
git cherry-pick commit-hash

# Cherry-pick multiple commits
git cherry-pick commit1 commit2 commit3

# Cherry-pick range of commits
git cherry-pick commit1..commit3

# Continue after resolving conflicts
git cherry-pick --continue

# Abort cherry-pick
git cherry-pick --abort

Example:

# Found a bug fix in develop that's needed in main
git log develop --oneline
# Output:
# abc1234 Fix critical security issue
# def5678 Add new feature

# Switch to main and cherry-pick fix
git checkout main
git cherry-pick abc1234

# The fix is now in main branch

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Tagging

Mark specific commits as important (usually for releases).

# Create lightweight tag
git tag v1.0.0

# Create annotated tag
git tag -a v1.0.0 -m "Version 1.0.0 release"

# Tag previous commit
git tag v1.0.0 commit-hash

# List all tags
git tag

# View tag details
git show v1.0.0

# Push tag to remote
git push origin v1.0.0

# Push all tags
git push origin --tags

# Delete local tag
git tag -d v1.0.0

# Delete remote tag
git push origin --delete v1.0.0

Example:

# Ready for release
git tag -a v1.5.0 -m "Release version 1.5.0 - Major stability improvements"

# Push to remote
git push origin v1.5.0

# Users can now download this specific version

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Reflog (Reference Logs)

Recover lost commits using reference logs.

# View all reference changes
git reflog

# Show reflog for specific branch
git reflog show branch-name

# Recover deleted branch
git checkout -b restored-branch abc1234

# View reflog for specific time
git reflog --date=short

Example:

# Accidentally deleted a branch
git reflog
# Output shows: abc1234 HEAD@{0}: checkout: moving from feature-x to main

# Recover the branch
git checkout -b feature-x abc1234

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Common Workflows

Feature Branch Workflow

Standard workflow for feature development.

# 1. Create feature branch from main
git checkout main
git pull origin main
git checkout -b feature/login-page

# 2. Work on feature
echo "login form" > login.html
git add login.html
git commit -m "Add login form"

echo "login styles" > login.css
git add login.css
git commit -m "Add login page styles"

# 3. Push to remote
git push -u origin feature/login-page

# 4. Create Pull Request on GitHub
# (Request reviewers and address feedback)

# 5. Merge to main (on GitHub or locally)
git checkout main
git pull origin main
git merge feature/login-page

# 6. Delete branch
git branch -d feature/login-page
git push origin --delete feature/login-page

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Git Flow Workflow

Complex workflow with develop and main branches.

# Main branches: main (production), develop (development)

# Create release branch
git checkout -b release/v1.0.0 develop

# Make release commits
echo "v1.0.0" > version.txt
git add version.txt
git commit -m "Bump version to 1.0.0"

# Merge to main
git checkout main
git merge --no-ff release/v1.0.0
git tag -a v1.0.0 -m "Release version 1.0.0"

# Merge back to develop
git checkout develop
git merge --no-ff release/v1.0.0

# Delete release branch
git branch -d release/v1.0.0

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Forking & Contributing to Others' Projects

# 1. Fork repository on GitHub (click Fork button)

# 2. Clone your fork
git clone https://github.com/YOUR_USERNAME/project.git
cd project

# 3. Add upstream remote
git remote add upstream https://github.com/ORIGINAL_OWNER/project.git

# 4. Create feature branch
git checkout -b feature/improvement
echo "improvement" > feature.js
git add feature.js
git commit -m "Add improvement"

# 5. Push to your fork
git push origin feature/improvement

# 6. Create Pull Request to original repository

# 7. Sync with upstream if needed
git fetch upstream
git rebase upstream/main

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Handling Merge Conflicts

# Attempt merge that causes conflicts
git merge feature-branch

# View conflict status
git status

# Edit files to resolve conflicts
# (Files will have markers like <<<<<<<, =======, >>>>>>>)

# After resolving
git add resolved-file.js

# Complete merge
git commit -m "Resolve merge conflicts"

# Or abort if merge went wrong
git merge --abort

Example Conflict Marker:

<<<<<<< HEAD
function calculateTotal(items) {
  return items.reduce((sum, item) => sum + item.price, 0);
}
=======
function calculateTotal(items) {
  let total = 0;
  for (let item of items) {
    total += item.price;
  }
  return total;
}
>>>>>>> feature-branch

Resolution: Keep the version you want or combine both. Remove conflict markers.

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Best Practices

Commit Message Guidelines

# Good: Clear, descriptive, imperative mood
git commit -m "Add user authentication module"
git commit -m "Fix dropdown menu alignment on mobile"
git commit -m "Update API endpoints documentation"

# Bad: Vague or unclear
git commit -m "Fix stuff"
git commit -m "Changed things"
git commit -m "wip"

# Detailed commit message
git commit -m "Implement password reset feature

- Add email verification
- Add password strength validation
- Add token expiration after 24 hours
- Add recovery email template"

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.gitignore

Prevent unnecessary files from being tracked.

Example .gitignore:

# Dependencies
node_modules/
venv/
env/

# Environment variables
.env
.env.local
.env.*.local

# IDE
.vscode/
.idea/
*.swp
*.swo

# OS
.DS_Store
Thumbs.db

# Build output
dist/
build/
*.log

# Temporary files
*.tmp
~$*.xlsx

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Branching Best Practices

# ✓ Good: Descriptive names
git checkout -b feature/user-profile
git checkout -b bugfix/memory-leak
git checkout -b docs/api-endpoints

# ✗ Bad: Generic or unclear
git checkout -b feature1
git checkout -b fix
git checkout -b test

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Code Review Practices

1. Create descriptive Pull Requests with clear title and description
2. Request specific reviewers who understand the code
3. Link related issues in the PR description
4. Keep PRs focused on single features or fixes
5. Respond to feedback promptly and professionally
6. Test thoroughly before requesting review

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Keeping Repository Clean

# Delete local branches that no longer exist on remote
git fetch --prune

# Compress repository
git gc

# View large files in history
git rev-list --all --objects | sort -k 2 | tail -10

# Remove large file from history (careful!)
git filter-branch --tree-filter 'rm -f path/to/large/file' HEAD

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Common Mistakes & Recovery

Mistake: Committed to wrong branch

# Save the commit
git log --oneline -n 1
# Copy the commit hash

# Undo commit on current branch
git reset HEAD~1

# Switch to correct branch
git checkout correct-branch

# Reapply commit
git cherry-pick commit-hash

Mistake: Uncommitted changes before switching branches

# Save work
git stash

# Switch branches
git checkout other-branch

# Restore work when ready
git checkout original-branch
git stash pop

Mistake: Pushed wrong commit

# Option 1: Create a revert commit (safe for public branches)
git revert commit-hash
git push

# Option 2: Force push (only for private branches!)
git reset HEAD~1
git push --force-with-lease origin branch-name

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Performance Tips

# Shallow clone (faster for large repos)
git clone --depth 1 https://github.com/username/repo.git

# Sparse checkout (clone only certain directories)
git clone --sparse https://github.com/username/repo.git

# Clean up repository
git gc --aggressive

# Check repository size
git count-objects -v

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Useful Aliases

Add to .gitconfig for faster commands:

# Add aliases
git config --global alias.st status
git config --global alias.co checkout
git config --global alias.br branch
git config --global alias.ci commit
git config --global alias.unstage 'reset HEAD --'
git config --global alias.last 'log -1 HEAD'
git config --global alias.visual 'log --graph --oneline --all'

# Usage
git st              # Instead of git status
git co main         # Instead of git checkout main
git ci -m "msg"     # Instead of git commit -m "msg"
git visual          # Instead of git log --graph --oneline --all

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Resources

• Git Official Documentation
• GitHub Docs
• Pro Git Book
• GitHub Learning Lab
• Atlassian Git Tutorials

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Quick Reference

Command	Purpose
git init	Initialize repository
git clone <url>	Clone repository
git status	Check status
git add .	Stage all changes
git commit -m "msg"	Commit changes
git push	Push to remote
git pull	Pull from remote
git branch	List branches
git checkout -b name	Create new branch
git merge name	Merge branch
git log	View history
git diff	Show changes

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Last Updated: January 5, 2026

License: MIT

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This guide covers Git and GitHub essentials. For additional topics, refer to the official documentation.