Anatomy of a Commit Message

1. Subject Line

The Subject Line is the first line of your commit message. Often the subject alone is enough, but if it's not and you need a body be sure to separate the subject and body with a blank line.

  • First line of a commit message
  • Often the only part you'll need
  • Separated from the body by a blank line
  • Soft limit of 50 characters, hard limit of 69
    • Github's interface truncates the subject line at 69 characters
  • Capitalize!
  • Don't end with a period
  • Use the imperative mood
    • Git itself uses the imperative mood when it creates a commit on your behalf
    • We usually write in the indicative mood, which is more about reporting facts
    • To help, the subject line should always complete the sentence:
      • "If applied, this commit will..."

2. Body

  • Wrap the body at 72 characters
    • This give git plenty of room to indent text while still keeping things under 80 characters.
  • Use the body to explain what and why vs. how
    • The code tells us the how, the body of your commit message should tell us what and why.

Sample Commit Messages

Bad

Fixed the thing

Good

Fix all the broken things

There were some broken things so I refactored many codes to simplify
and fix all the things.
  • Uses the imperative mood for the subject line
  • Separates the subject from the body with a single blank line
  • Describes the what and why in the body


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