<b><i>Background:</i></b> This review addresses the intricate spectrum of gastroesophageal reflux disease (GERD), a condition affecting 10–30% of the Western population. GERD is characterized by the backflow of gastric contents into the esophagus, causing typical and atypical symptoms. Its pathophysiology involves various factors such as hiatal hernia, esophageal motor disorders, and dietary triggers. The review explores the complexities of GERD spectrum, including nonerosive reflux disease (NERD), reflux hypersensitivity (RH), and functional heartburn (FH). <b><i>Summary:</i></b> The diagnostic process for GERD, based on the Lyon Consensus 2.0 criteria, encompasses clinical evaluation, endoscopy, and functional tests, including pH-impedance and wireless-pH monitoring. NERD, a significant subset of GERD, is defined by reflux symptoms and abnormal reflux burden without mucosal damage. RH, classified under functional esophageal disorders by Rome IV criteria, presents with typical esophageal symptoms associated with reflux but lacks of structural, inflammatory, or motor causes. FH is identified by heartburn with normal endoscopy, reflux testing, and esophageal manometry results. The management of RH and FH, focusing on reducing esophageal hypersensitivity, varies from standard GERD treatments. <b><i>Key Messages:</i></b> The review emphasizes the necessity of personalized treatment strategies due to the complexity and overlap of GERD subtypes. It highlights the importance of a multidisciplinary approach, involving gastroenterologists, psychologists, and other specialists, to improve patient outcomes and quality of life. The article underscores that understanding the distinctions and overlaps among NERD, RH, and FH is crucial for effective management, and the need for innovative approaches in diagnosis and treatment to address the unique challenges of each subtype.