Patient safety is a global concern and is the most important domains of health-care quality. Medical error is a major patient safety concern, causing increase in health-care cost due to mortality, morbidity, or prolonged hospital stay. A definition for patient safety has emerged from the health care quality movement that is equally abstract, with various approaches to the more concrete essential components. Patient safety was defined by the IOM as "the prevention of harm to patients." Emphasis is placed on the system of care delivery that prevents errors; learns from the errors that do occur; and is built on a culture of safety that involves health care professionals, organizations, and patients. Patient safety culture is a complex phenomenon. Patient safety culture assessments, required by international accreditation organizations, allow healthcare organizations to obtain a clear view of the patient safety aspects requiring urgent attention, identify the strengths and weaknesses of their safety culture, help care giving units identify their existing patient safety problems, and benchmark their scores with other hospitals.