This section details respiratory system disorders in children. It emphasizes that children's respiratory systems differ from those of adults both anatomically and physiologically; airway narrowing, incomplete alveolar development, and limited respiratory reserve make children more susceptible to infections and respiratory failure. The respiratory system is examined in terms of upper and lower respiratory tracts, and the relationship between gas exchange, respiratory mechanisms, and metabolic requirements in children is explained. Furthermore, the importance of diagnostic methods such as physical examination, assessment of breath sounds, oxygen saturation, chest X-ray, and pulmonary function tests is highlighted. This section details upper respiratory tract diseases, including acute rhinopharyngitis, pharyngitis, tonsillitis, croup, sinusitis, laryngitis, and acute otitis media. It notes that most of these diseases are viral in origin, common in children, and typically present with symptoms such as cough, fever, runny nose, sore throat, and shortness of breath. Lower respiratory tract diseases include bronchiolitis, pneumonia, asthma, bronchitis, cystic fibrosis, and tuberculosis. It is specifically noted that bronchiolitis is common in infants, and asthma is the most common chronic disease of childhood. In these cases, early diagnosis, oxygen support, appropriate medication, hydration, and infection control are among the fundamental approaches. A significant portion of the section is devoted to nursing care. The importance of a child and family-centered care approach is emphasized; respiratory monitoring, airway patency, appropriate positioning, family education, and infection control are identified as key elements of nursing care. It is highlighted that current approaches include the increasing use of non-invasive ventilation techniques, home care models, and digital monitoring systems.