This chapter offers a detailed examination of obstructive sleep apnea (OSA), exploring its connection to respiratory physiology and the spectrum of sleep-disordered breathing types. It delves into the pathophysiology of OSA, alongside its epidemiology, risk factors, and clinical manifestations. The chapter outlines diagnostic criteria and severity classification, emphasizing the importance of polysomnography (PSG) and home sleep apnea testing (HSAT). It also addresses the various comorbidities linked with OSA, including cardiovascular, metabolic, and neurological conditions. A key focus is on patient education and the need for a multidisciplinary management approach, highlighting the effectiveness of positive airway pressure (PAP) therapy and alternative treatment options. Overall, this chapter provides healthcare professionals with a thorough understanding of OSA and its comprehensive management.