Types:

feat: New feature
fix: Bug fix
docs: Documentation only
refactor: Code change that neither fixes bug nor adds feature
perf: Performance improvement
test: Adding or updating tests
chore: Build process, dependencies, tooling

Examples:

feat(auth): add OAuth2 authentication

Implements OAuth2 flow using Google provider.
Includes token refresh and validation.

Closes #123

fix(api): handle null response in user endpoint

Previously crashed when user not found.
Now returns 404 with error message.

perf(db): optimize user query with index

Reduces query time from 500ms to 50ms.

Atomic Commits

# Good: Each commit does one thing
git commit -m "feat: add user authentication"
git commit -m "test: add auth tests"
git commit -m "docs: update API docs for auth"

# Bad: Multiple unrelated changes
git commit -m "add auth, fix bugs, update docs"

Branching Strategy

Git Flow (Feature Branches)

# Create feature branch from main
git checkout main
git pull origin main
git checkout -b feature/user-authentication

# Work on feature with regular commits
git add src/auth.py
git commit -m "feat(auth): implement login endpoint"

# Keep branch updated with main
git checkout main
git pull origin main
git checkout feature/user-authentication
git rebase main  # Or: git merge main

# Push and create PR
git push -u origin feature/user-authentication

Trunk-Based Development

# Work directly on main with short-lived branches
git checkout main
git pull origin main
git checkout -b fix/null-pointer
# Make small change
git commit -m "fix: handle null in user query"
git push origin fix/null-pointer
# Merge immediately via PR

Common Workflows

Updating Branch with Latest Changes

# Option 1: Rebase (cleaner history)
git checkout feature-branch
git fetch origin
git rebase origin/main

# Resolve conflicts if any
git add resolved_file.py
git rebase --continue

# Option 2: Merge (preserves history)
git checkout feature-branch
git merge origin/main

Undoing Changes

# Undo last commit (keep changes)
git reset --soft HEAD~1

# Undo last commit (discard changes)
git reset --hard HEAD~1

# Undo changes to specific file
git checkout -- file.py

# Revert a commit (creates new commit)
git revert abc123

# Amend last commit
git add forgotten_file.py
git commit --amend --no-edit

Stashing Work

# Save current work temporarily
git stash

# List stashes
git stash list

# Apply most recent stash
git stash pop

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

# Create named stash
git stash save "WIP: authentication feature"

Cherry-Picking Commits

# Apply specific commit from another branch
git cherry-pick abc123

# Cherry-pick multiple commits
git cherry-pick abc123 def456

# Cherry-pick without committing
git cherry-pick -n abc123

Resolving Conflicts

# When conflicts occur during merge/rebase
# 1. Check conflicted files
git status

# 2. Edit files to resolve conflicts
# Look for conflict markers:
<<<<<<< HEAD
Your changes
=======
Their changes
>>>>>>> branch-name

# 3. Mark as resolved
git add resolved_file.py

# 4. Continue operation
git rebase --continue  # or git merge --continue

Viewing History

# Compact log
git log --oneline -10

# Graphical log
git log --graph --oneline --all

# Commits by author
git log --author="John Doe"

# Commits affecting specific file
git log -- path/to/file.py

# See changes in commit
git show abc123

# Compare branches
git diff main..feature-branch

Branch Management

# List branches
git branch -a  # All branches (local + remote)

# Delete local branch
git branch -d feature-branch  # Safe delete (merged only)
git branch -D feature-branch  # Force delete

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

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

# Track remote branch
git checkout --track origin/feature-branch

Advanced Operations

Interactive Rebase

# Edit last 3 commits
git rebase -i HEAD~3

# Options in editor:
# pick = use commit
# reword = change commit message
# edit = stop to amend commit
# squash = combine with previous commit
# fixup = like squash but discard message
# drop = remove commit

Bisect (Find Bug Introduction)

# Start bisect
git bisect start
git bisect bad  # Current version has bug
git bisect good v1.0.0  # This version was good

# Git checks out middle commit
# Test if bug exists
git bisect bad  # if bug exists
git bisect good  # if bug doesn't exist

# Git narrows down until finding first bad commit
git bisect reset  # Return to original branch

Blame (Find Who Changed Line)

# See who last modified each line
git blame file.py

# Ignore whitespace changes
git blame -w file.py

# Show specific line range
git blame -L 10,20 file.py

Git Hooks

# Pre-commit hook (runs before commit)
# .git/hooks/pre-commit
#!/bin/bash
npm run lint
npm test

# Pre-push hook (runs before push)
# .git/hooks/pre-push
#!/bin/bash
npm run test:integration

Best Practices

✅ DO

Commit frequently with atomic changes
Write clear, descriptive commit messages
Pull before push to avoid conflicts
Review changes before committing (git diff --staged)
Use branches for features and fixes
Keep commits small and focused

❌ DON'T

Commit sensitive data (use .gitignore)
Commit generated files (build artifacts, node_modules)
Force push to shared branches (git push --force)
Commit work-in-progress to main
Include multiple unrelated changes in one commit
Rewrite public history

.gitignore Patterns

# Dependencies
node_modules/
venv/
__pycache__/

# Build outputs
dist/
build/
*.pyc
*.o
*.exe

# IDE
.vscode/
.idea/
*.swp

# Secrets
.env
*.key
*.pem
secrets.yml

# OS
.DS_Store
Thumbs.db

# Logs
*.log
logs/

Quick Command Reference

# Status and diff
git status
git diff
git diff --staged

# Commit
git add .
git commit -m "message"
git push

# Branch
git branch
git checkout -b branch-name
git merge branch-name

# Update
git pull
git fetch

# Undo
git reset HEAD~1
git checkout -- file
git revert commit-hash

# History
git log
git log --oneline
git show commit-hash

Remember

Commit often - Small commits are easier to review and revert
Descriptive messages - Future you will thank present you
Pull before push - Stay synchronized with team
Use branches - Keep main stable
Review before commit - Check what is being committed

Atomic Commits

Branching Strategy

Git Flow (Feature Branches)

Trunk-Based Development

Common Workflows

Updating Branch with Latest Changes

Undoing Changes

Stashing Work

Cherry-Picking Commits

Resolving Conflicts

Viewing History

Branch Management

Tags

Advanced Operations

Interactive Rebase

Bisect (Find Bug Introduction)

Blame (Find Who Changed Line)

Git Hooks

Best Practices

✅ DO

❌ DON'T

.gitignore Patterns

Quick Command Reference

Remember

git-workflow

Git Workflow

Commit Best Practices

Conventional Commits Format