What Is Code Review? | Vantage

Code Review Code review is the systematic examination of source code by engineers other than the author before it is merged into the main branch. Reviewers check for correctness, security vulnerabilities, adherence to team conventions, test coverage, and maintainability. Most teams implement code review via pull requests on GitHub, GitLab, or Bitbucket, where reviewers leave inline comments and approve or request changes.

Why code review matters

Code review is one of the highest-leverage engineering practices because it catches defects before they reach production, spreads knowledge about the codebase across the team, enforces consistent standards, and creates a natural forcing function for writing readable, well-structured code. Studies consistently show that code review finds more defects per hour than any other testing technique.

How it works

The author opens a pull request with a description of the change. Reviewers examine the diff, leave comments on specific lines, and either approve, request changes, or comment. The author addresses feedback and updates the PR. When a configured number of reviewers approve, the PR is merged. Automated checks (CI, linting, tests) run in parallel to catch mechanical issues before the human review.

Common mistakes

• Reviewing too much code at once — PRs over 400 lines get cursory reviews

• No context in the PR description — reviewers cannot evaluate correctness without knowing intent

• Conflating style preferences with actual defects in review comments

• Review as a gate, not a conversation — using approval as a stamp rather than a collaborative process

• Not including tests in review scope — a PR without tests reviewing only the implementation misses half the picture