Definition
Code review is the practice of having one or more developers examine another developer’s code changes before those changes are accepted into the project. It typically happens through a pull request, where reviewers read through the proposed changes, check for bugs, assess whether the approach is sound, and verify that the code follows the team’s standards. Reviewers leave comments, ask questions, and may request changes before giving their approval. It is a collaborative process, not an adversarial one — the goal is better software, not catching people out.
Why It Matters
Code review is one of the most effective quality practices in software development. Studies consistently show that reviewed code has significantly fewer defects than code that goes straight to production. Beyond catching bugs, it spreads knowledge across the team so that no single developer is the only person who understands a critical part of the system. It also maintains consistency — when multiple developers follow the same patterns, the codebase stays maintainable rather than becoming a patchwork of different styles. If your development team is skipping code reviews, you are accepting more risk with every release.
Example
A junior developer builds a reporting feature that works correctly but loads all report data into memory at once. During code review, a senior developer points out that this approach will fail when the dataset grows beyond a few thousand records and suggests a paginated approach instead. The junior developer learns the pattern, applies it, and the feature ships in a way that will scale with your business rather than breaking under load six months later.