The chapter discusses the Clavien–Dindo classification of surgical complications, which is a standardized method for categorizing and grading these complications. The classification aims to improve quality assurance in surgery by providing a consistent framework for reporting and analyzing surgical outcomes. The Clavien–Dindo classification is based on the therapy required to treat the complication, with five grades ranging from minor issues to major interventions. This approach minimizes subjectivity and subjective interpretation, making it easier to track and compare surgical performance across different hospitals and over time. The chapter also highlights the importance of reliable outcome data in improving surgical quality and patient care, driven by rising healthcare costs, constrained resources, and increasing patient awareness.The chapter discusses the Clavien–Dindo classification of surgical complications, which is a standardized method for categorizing and grading these complications. The classification aims to improve quality assurance in surgery by providing a consistent framework for reporting and analyzing surgical outcomes. The Clavien–Dindo classification is based on the therapy required to treat the complication, with five grades ranging from minor issues to major interventions. This approach minimizes subjectivity and subjective interpretation, making it easier to track and compare surgical performance across different hospitals and over time. The chapter also highlights the importance of reliable outcome data in improving surgical quality and patient care, driven by rising healthcare costs, constrained resources, and increasing patient awareness.