C1: No Inappropriate Information
Comments shouldn't hold metadata. Use Git for author names, change history, ticket numbers, and dates. Comments are for technical notes about code only.
C2: Delete Obsolete Comments
If a comment describes code that no longer exists or works differently, delete it immediately. Stale comments become "floating islands of irrelevance and misdirection."
C3: No Redundant Comments
// Bad - the code already says this
i += 1; // increment i
user.save(); // save the user
// Good - explains WHY, not WHAT i += 1; // compensate for zero-indexing in display
## C4: Write Comments Well
If a comment is worth writing, write it well:
- Choose words carefully
- Use correct grammar
- Don't ramble or state the obvious
- Be brief
## C5: Never Commit Commented-Out Code
```ts
// DELETE THIS - it's an abomination
// function oldCalculateTax(income: number): number {
// return income * 0.15;
// }
Who knows how old it is? Who knows if it's meaningful? Delete it. Git remembers everything.
The Goal
The best comment is the code itself. If you need a comment to explain what code does, refactor first, comment last.