Code Review
Code review is the practice of having one or more developers examine a proposed change to a codebase before it is merged, checking for correctness, design quality, and adherence to team standards.
Definition
Code review is the practice of having one or more developers examine a proposed change to a codebase before it is merged, checking for correctness, design quality, and adherence to team standards.
Overview
Most modern teams review code through a pull request: a developer proposes a set of changes, and one or more reviewers comment on the diff, request modifications, or approve it before it merges into the main codebase. The goal is to catch bugs, design problems, and maintainability issues before they reach production, while also spreading knowledge of the codebase across the team and giving less experienced developers feedback from more experienced colleagues. Effective code review focuses on things automated tools cannot easily check — is this the right approach architecturally, does this change handle edge cases correctly, is the code understandable to someone who didn't write it — while linting and code formatters handle style and mechanical issues automatically, so human reviewers do not need to spend their attention on formatting nitpicks. Teams often set expectations around review scope (smaller pull requests are easier and faster to review well), turnaround time, and the tone of feedback, since review can become a source of friction if comments feel overly critical or arrive too slowly to keep development moving. Code review complements, rather than replaces, other quality practices: automated unit testing verifies behavior mechanically, while review adds human judgment about design, readability, and long-term maintainability that tests alone cannot capture. Some teams supplement or substitute asynchronous review with pair programming, reviewing continuously as code is written instead of after the fact, though most teams use some combination of both depending on the risk and complexity of the change.
Key Concepts
- Reviewers examine a proposed code change before it is merged
- Commonly organized around pull requests in tools like GitHub or GitLab
- Catches bugs, design flaws, and maintainability issues before production
- Spreads codebase knowledge and mentors less experienced developers
- Complements automated linting and formatting, which handle mechanical issues
- Smaller, focused pull requests are generally easier to review thoroughly
- Works alongside, not instead of, automated testing
Use Cases
Frequently Asked Questions
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