PRINCE2 (Projects IN Controlled Environments) is a best practice project management methodology recognized by the UK government. It focuses on dividing projects into manageable stages, with an emphasis on business justification, organization, and controls. Key techniques include product-based planning, quality reviews, change control, and configuration management. While less comprehensive than PMBOK, PRINCE2 provides a prescriptive process structure and can complement PMBOK by helping structure a project methodology and implement techniques like organization and change control. Understanding both PMBOK and PRINCE2 can provide project managers with a comprehensive skillset.