<b><i>Background:</i></b> Functional endoscopy signifies a significant advancement in gastrointestinal examination, integrating motor function assessments alongside routine endoscopy findings. Traditional gastrointestinal endoscopy primarily focuses on the detection of early-stage cancer by identifying morphological changes within the gastrointestinal tract. These alterations include modifications in lumen structure, color tone, and surface patterns, which can be diagnosed using endoscopic images that assess these morphological changes. In contrast, functional endoscopy aims to dynamically evaluate the peristaltic movements of the digestive tract and the presence or movement of reflux of digestive fluids during the endoscopic procedure. It also seeks to identify morphological changes such as hiatal hernias, as observed in conventional endoscopy. Consequently, relying solely on endoscopic images proves inadequate for diagnosis, necessitating continuous observation of these dynamic movements. <b><i>Summary:</i></b> The endoscopic pressure study integrated system (EPSIS) serves as an exemplar of functional endoscopy. It incorporates a stress test to assess the functionality of the lower esophageal sphincter (LES) through intragastric insufflation. A crucial element of EPSIS evaluation is the identification of the scope holding sign (SHS), which signifies LES contraction. EPSIS also encompasses the observation of esophageal peristaltic waves and the auditory detection of burping, providing a comprehensive diagnostic approach while observing the sphincter from a retroflex view on the stomach side. By integrating these dynamic findings, functional endoscopy offers an efficient method for diagnosing functional gastrointestinal diseases, such as gastroesophageal reflux disease (GERD). <b><i>Key Messages:</i></b> Functional endoscopy combines motor function assessments with traditional endoscopy, enhancing the diagnostic capabilities of gastrointestinal examinations. Traditional endoscopy focuses on identifying morphological changes, while functional endoscopy evaluates dynamic movements, reflux, and sphincter functionality. EPSIS exemplifies functional endoscopy, featuring a stress test and the SHS for LES contraction assessment. EPSIS provides a comprehensive approach to diagnose GERD by integrating dynamic observations.