Writing good commit messages in Git - Mini Project: Build & Apply

Writing Good Commit Messages

📖 Scenario: You are working on a small project with your friend. You want to keep track of your changes clearly so both of you understand what was done and why. Writing good commit messages helps everyone on the team stay organized and makes it easier to find changes later.

🎯 Goal: Learn how to write clear and helpful git commit messages by creating commits with specific messages following best practices.

📋 What You'll Learn

Create a git repository

Make a file change

Write a commit message with a short summary

Add a detailed description in the commit message body

Use proper formatting for commit messages

💡 Why This Matters

🌍 Real World

Writing clear commit messages is like keeping a diary of your work. It helps you and your team remember what was done and why, making collaboration smoother.

💼 Career

Employers expect developers to write meaningful commit messages. This skill improves teamwork, code reviews, and project maintenance.

1

Initialize Git Repository and Create a File

Initialize a new git repository in your current folder by running git init. Then create a file called README.md with the exact content # Project Title.

Git

# Run git init and create README.md with '# Project Title' inside
# Your code here

Hint

Use git init to start a new repository. Use echo or a text editor to create README.md with the exact text.

2

Add the File and Prepare to Commit

Add the file README.md to the git staging area using git add README.md. This prepares the file to be committed.

Git

git init

echo "# Project Title" > README.md

# Add README.md to staging area
# Your code here

Hint

Use git add README.md to stage the file for commit.

3

Write a Commit with a Short Summary

Create a commit with the message Initial commit using git commit -m "Initial commit". This message is a short summary of the change.

Git

git init

echo "# Project Title" > README.md

git add README.md

# Commit with message 'Initial commit'
# Your code here

Hint

Use git commit -m "Your message" to commit with a short message.

4

Write a Commit with a Detailed Message

Modify the README.md file by adding the line Project description goes here.. Then add the file again with git add README.md. Finally, create a commit with a detailed message using git commit -m "Add project description" -m "Added a description line to README.md to explain the project purpose.". The first -m is the short summary, the second -m is the detailed body.

Git

git init

echo "# Project Title" > README.md

git add README.md

git commit -m "Initial commit"

# Add description line to README.md
# Add README.md to staging
# Commit with short and detailed messages
# Your code here

Hint

Use echo with >> to append text. Use two -m options in git commit for short and detailed messages.

Practice

1. What is the main purpose of a good commit message in Git?

easy

A. To list all files changed in the commit

B. To explain what changes were made and why

C. To include the entire code change in the message

D. To write a long story about the project history

Solution

1. Step 1: Understand the role of commit messages

   Commit messages should clearly explain what was changed and why, helping others understand the purpose.

2. Step 2: Identify the best option

   To explain what changes were made and why correctly states the purpose, while others focus on irrelevant or incorrect details.

3. Final Answer:

   To explain what changes were made and why -> Option B

4. Quick Check:

   Good commit message = explain what and why [OK]

Hint: Focus on explaining changes and reasons, not details [OK]

Common Mistakes:

• Listing files instead of explaining changes
• Writing too much unrelated history
• Including code in the message

2. Which of the following is the correct format for a good Git commit message?

easy

A. A message with only emojis

B. A long paragraph without a summary line

C. Only a list of changed files

D. A short summary line followed by a blank line and detailed explanation

Solution

1. Step 1: Recall Git commit message format

   A good commit message starts with a short summary line, then a blank line, then optional details.

2. Step 2: Match options to format

   A short summary line followed by a blank line and detailed explanation matches this format exactly; others do not follow best practices.

3. Final Answer:

   A short summary line followed by a blank line and detailed explanation -> Option D

4. Quick Check:

   Summary line + blank line + details = correct format [OK]

Hint: Use a short summary line, then details after a blank line [OK]

Common Mistakes:

• Skipping the blank line between summary and details
• Writing only a long paragraph
• Using emojis without explanation

3. Given this commit message:
Fix login bug
What is missing to make it a good commit message?

medium

A. A detailed explanation of why the bug was fixed

B. A list of all files changed

C. A longer summary line

D. The author's email

Solution

1. Step 1: Analyze the commit message content

   The message only has a short summary but lacks explanation of why the bug was fixed.

2. Step 2: Identify what improves clarity

   Adding a detailed explanation helps others understand the reason behind the fix.

3. Final Answer:

   A detailed explanation of why the bug was fixed -> Option A

4. Quick Check:

   Good message = what + why, missing why here [OK]

Hint: Add why the change was made, not just what [OK]

Common Mistakes:

• Only writing a short summary
• Listing files instead of explanation
• Adding unrelated info like author email

4. You wrote this commit message:
fix login bug
What is the main problem with this message?

medium

A. It includes a blank line after the summary

B. It is too long and detailed

C. It uses lowercase and lacks a capitalized summary

D. It uses past tense instead of present tense

Solution

1. Step 1: Check capitalization in commit messages

   Good commit messages start with a capitalized summary line.

2. Step 2: Evaluate the given message

   The message starts with lowercase 'fix', which is not recommended.

3. Final Answer:

   It uses lowercase and lacks a capitalized summary -> Option C

4. Quick Check:

   Summary line should start capitalized [OK]

Hint: Always capitalize the first letter of the summary line [OK]

Common Mistakes:

• Starting summary with lowercase letter
• Making summary too long
• Ignoring tense conventions

5. You want to write a commit message for adding a new feature that improves search speed by caching results. Which commit message is best?

hard

A. Add caching to improve search speed

Implemented a cache layer to store recent search results, reducing response time.

B. Improved search speed by adding cache

Cache added.

C. Added cache

This commit adds cache.

D. Fix search speed

Cache implemented.

Solution

1. Step 1: Evaluate clarity and detail in options

   Add caching to improve search speed Implemented a cache layer to store recent search results, reducing response time. has a clear summary and detailed explanation of what and why.

2. Step 2: Compare other options

   The other options are vague, use incorrect tense or verbs (such as 'Fix' for a new feature), or lack detailed explanation.

3. Final Answer:

   Add caching to improve search speed Implemented a cache layer to store recent search results, reducing response time. -> Option A

4. Quick Check:

   Clear summary + detailed why = best commit message [OK]

Hint: Use clear summary and explain why change matters [OK]

Common Mistakes:

• Using vague summaries
• Wrong verbs like 'Fix' for new features
• Too short or unclear explanations