Why Code Review Matters: Nine Compelling Reasons

Many Silicon Valley companies require every change to be reviewed by at least two people, and the author recounts how adopting mandatory code review after a new Google hire dramatically improved their team's quality.

1. Detecting bugs – The most obvious benefit is catching errors and surface best‑practice violations that the author may not have noticed.

2. Macro‑level knowledge sharing – Reviewing others' code exposes you to new technologies and techniques, helping you become a better engineer.

3. Micro‑level knowledge sharing (bus factor) – Involving more people with each piece of code reduces the risk that a single person’s departure will cripple the project.

4. Trend sharing – Code review forces discussions about ongoing work, allowing teams to align direction and roll back if needed.

5. Communication practice – Writing clear change descriptions and feedback hones the essential skill of precise written communication.

6. Historical record – Knowing that changes are reviewed encourages better commit messages, which become valuable when revisiting past work.

7. Precise discussion – Code provides an exact medium for debating algorithmic details that are hard to convey verbally.

8. Team cohesion – Regular reviews make the team feel like a unified group rather than isolated individuals.

9. Reading practice – Regularly reading others' code improves the readability and maintainability of your own code.

The author notes that reasons 2, 5, and 6 are personally the most important.