Writing good commit messages in Git - Step-by-Step Execution

Process Flow - Writing good commit messages

Start Commit

↓

Write short summary (<=50 chars)

↓

Add blank line

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Write detailed description

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Review message

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Save and close commit

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Commit recorded

This flow shows the steps to write a clear and helpful git commit message, starting with a short summary, then a blank line, followed by a detailed description.

Execution Sample

Git

git commit -m "Fix login bug"

# Detailed message:
# The login failed due to missing token check.
# Added token validation to fix the issue.

This commit message has a short summary and a detailed explanation separated by a blank line.

Process Table

Step	Action	Message Part	Result
1	Write short summary	Fix login bug	Summary line created
2	Add blank line		Blank line added after summary
3	Write detailed description	The login failed due to missing token check. Added token validation to fix the issue.	Detailed description added
4	Review message	Fix login bug The login failed due to missing token check. Added token validation to fix the issue.	Message ready to save
5	Save and close commit		Commit recorded with message

💡 Commit message saved and commit recorded in git history

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
commit_message		Fix login bug	Fix login bug	Fix login bug The login failed due to missing token check. Added token validation to fix the issue.	Fix login bug The login failed due to missing token check. Added token validation to fix the issue.

Key Moments - 3 Insights

Why do we add a blank line after the short summary?

The blank line separates the summary from the detailed description, making the message easier to read and follow, as shown in step 2 of the execution_table.

Can the short summary be too long?

Yes, it should be 50 characters or less to keep it concise and clear, as demonstrated in step 1 where the summary is short and direct.

What if I skip the detailed description?

Skipping the detailed description can make it harder for others to understand the reason behind the change. Step 3 shows adding details improves clarity.

Visual Quiz - 3 Questions

Look at the execution_table, what is the commit_message after step 3?

A Fix login bug The login failed due to missing token check. Added token validation to fix the issue.

B Fix login bug

C gub nigol xiF

D The login failed due to missing token check.

💡 Hint

Check the commit_message value in variable_tracker after step 3

At which step is the blank line added in the commit message?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Action' and 'Message Part' columns in execution_table for the blank line addition

If the short summary is longer than 50 characters, what is the likely effect?

A The commit message will be rejected by git

B The detailed description will be ignored

C The message will be harder to read and less clear

D The commit will fail to save

💡 Hint

Refer to key_moments about summary length and clarity

Concept Snapshot

Writing good commit messages:
- Start with a short summary (<=50 chars)
- Add a blank line after summary
- Write a detailed description explaining the change
- Review message before saving
- Clear messages help team understanding

Full Transcript

To write a good git commit message, start by writing a short summary line that briefly describes the change. This summary should be 50 characters or less to keep it concise. Next, add a blank line to separate the summary from the detailed description. Then write a detailed explanation of what was changed and why. Review the entire message to ensure clarity and helpfulness. Finally, save and close the commit message to record the commit. This process helps keep commit history clear and useful for everyone on the team.

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