Git — Commit

What is a Commit?

A commit is a snapshot of your project at a specific point in time. It records what changed, who made the change, when, and why.

The Two-Step Process

# Step 1: Stage changes
git add filename.txt

# Step 2: Commit
git commit -m "Add login page"

Why Stage First?

Staging lets you choose exactly which changes to include:

# You modified 3 files, but only want to commit 2
git add file1.txt file2.txt
git commit -m "Update file1 and file2"

Staging Files

# Stage a specific file
git add index.html

# Stage multiple files
git add index.html style.css script.js

# Stage all changes in current directory
git add .

# Stage all changes everywhere
git add -A

# Interactive staging (choose parts of files)
git add -p

Writing Commit Messages

Good Messages

git commit -m "Add user authentication"
git commit -m "Fix login button not responding on mobile"
git commit -m "Update README with installation steps"
git commit -m "Remove deprecated API endpoint"

Bad Messages

git commit -m "fixed stuff"
git commit -m "update"
git commit -m "asdfgh"
git commit -m "WIP"

Convention

<type>: <short description>

<optional body>

Types:

• feat — new feature
• fix — bug fix
• docs — documentation
• style — formatting
• refactor — code restructuring
• test — adding tests
• chore — maintenance

git commit -m "feat: add password reset functionality"
git commit -m "fix: resolve mobile menu not closing"
git commit -m "docs: update API documentation"

Viewing Commits

# Show recent commits
git log --oneline

# Show with details
git log --stat

# Show changes in each commit
git log -p

# Show last 5 commits
git log -5

# Show commit history as graph
git log --graph --oneline --all

Amending Commits

# Change the last commit message
git commit --amend -m "New message"

# Add forgotten files to last commit
git add forgotten-file.txt
git commit --amend --no-edit

Undoing Commits

# Undo last commit, keep changes staged
git reset --soft HEAD~1

# Undo last commit, keep changes unstaged
git reset HEAD~1

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

Commit Hashes

Each commit gets a unique 40-character hash:

# View full hashes
git log --format="%H"

# Use short hash
git show abc1234

# Reference commits
git diff abc1234 def5678

Practical Example

# Start a new feature
git checkout -b feature/login

# Make changes
echo "login form" > login.html
echo "styles" > login.css

# Stage and commit
git add login.html login.css
git commit -m "feat: add login page with form and styles"

# Make more changes
echo "validation" > login.js
git add login.js
git commit -m "feat: add form validation"

# Switch back to main
git checkout main

# Merge the feature
git merge feature/login

Best Practices

• Commit often — small, focused commits are easier to understand
• Don't commit half-done work — use git stash instead
• Write meaningful messages — future you will thank present you
• One logical change per commit — don't mix unrelated changes
• Never commit generated files — add them to .gitignore

Mini Practice

1. Create a file, stage it, and commit with a message
2. Modify the file, check git status, then commit again
3. Use git log to view your commit history
4. Amend a commit message with --amend
5. Create a branch, make commits, and merge back

Up Next

Next: Branches →