To review someone else’s pull request, first understand what it is meant to change, then inspect the diff file by file, look for specific risks, leave actionable comments, and submit a decision that matches your findings. GitHub is a useful example of this workflow, but other code-hosting services may use different controls, labels, and permission rules.
Start by understanding the change
Before judging the code, read the pull request description and any linked issue, discussion, or project context. Ask what problem the author is trying to solve and which parts of the change are intended to solve it. Conversation in the pull request can clarify decisions that are not obvious from the diff.
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GitHub describes pull requests as a way to turn code changes into a conversation. That is a useful frame for review: your task is not just to find faults, but to help the team assess the proposed change against its purpose. See GitHub’s overview of pull requests.
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Inspect the diff and track what you have reviewed
In GitHub, open the pull request’s Files changed tab and work through the files one at a time. Compare each change with the stated goal, and follow relevant code paths when necessary to understand how the edited code behaves.
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GitHub provides a Viewed control for files and a progress bar showing review coverage. Mark a file as viewed only after you have inspected it; for a large pull request, this makes it easier to see what remains and reduces the chance of silently skipping a file. The interface is specific to GitHub, but the underlying habit—reviewing systematically and tracking coverage—applies elsewhere. See GitHub’s proposed-change review guide.
Passing checks, builds, or code-scanning results can provide useful evidence, but they do not establish that a change meets its goal or handles every relevant case. Treat automation as input to the review, not a replacement for reading the changes. GitHub explains the role of checks in its pull request documentation.
Focus on consequential issues
Use the author’s stated goal to guide your attention. GitHub’s beginner review guide calls out bugs and logic errors, missing error handling, accessibility problems, and unclear code as examples worth noticing. They are useful prompts, not a complete checklist for every language or project.
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- Purpose: Does the change appear to address the problem described in the pull request?
- Behavior: Could the code produce an incorrect result or fail in a relevant case?
- Resilience: Are errors or unexpected inputs handled where they matter?
- Usability and accessibility: Could the change make an interface harder to use or exclude some users?
- Clarity: Is the behavior difficult to understand in a way that could hinder maintenance?
For a change that adds, updates, or removes dependencies, check what changed and consider available dependency-review or security findings. GitHub documents tools such as dependency review and code scanning; whether they are available depends on the repository’s configuration and the features enabled for it.
Write feedback the author can act on
When a concern relates to a specific line, attach a comment there. Describe the behavior or risk you observed, and ask a focused question if the intent is unclear. A useful comment gives the author enough context to investigate rather than simply announcing that something seems wrong.
If you know the precise replacement, GitHub lets reviewers put it in a suggestion block that the author can apply. Use that when the proposed edit is clear; use a question or explanation when the right change depends on context. Review comments and conversations appear in the pull request timeline. See GitHub’s commenting guide and its guide to giving review feedback.
Distinguish a defect from a preference. If you are suggesting a different style or approach, explain its practical effect or frame it as a question rather than implying the code is broken.
Choose the review decision that matches your findings
After reviewing, add a summary and choose the decision that best communicates your conclusion. GitHub offers three review decisions:
Best Value
| Decision | Signal to the author and team | Merge effect |
|---|---|---|
| Comment | You are leaving feedback without signaling approval or requesting a change. | Does not itself signal approval or a required change. |
| Approve | You consider the changes ready to merge based on your review. | Records approval; whether approval is required for merging depends on repository rules. |
| Request changes | You are flagging something you believe the author should address. | It does not universally block a merge. The effect depends on repository rules and reviewer permissions. |
Do not assume that a request for changes always prevents merging: GitHub says that outcome depends on configured rules and the reviewer’s permissions, and repository owners or administrators may have merge authority in documented circumstances. Check the repository’s own policy when the effect matters. GitHub explains the choices and qualifications in its review feedback documentation and proposed-change review guide.
Use automated review tools as supporting evidence
Dependency review and code scanning can help surface risks, and GitHub also documents Copilot review assistance. These tools can point you toward issues or offer suggestions, but they do not replace understanding the pull request’s intent and checking whether the change behaves as needed. Availability and behavior depend on the tools and settings enabled for the repository. See GitHub’s documentation on Copilot code review.
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