What is code review and what are its benefits?

Code review is systematic examination of code changes by peers before merging. Benefits: catches bugs early, improves code quality, shares knowledge across team, enforces coding standards, mentors junior developers. Best practices: keep reviews small (<400 lines), review promptly, focus on code not person, use checklists, automate style checking. Tools: GitHub Pull Requests, GitLab Merge Requests, Gerrit. Reviews should be constructive and aim for continuous improvement.