The scope of gastrointestinal endoscopy is limited by the fact that endoscopy is a visual method dependent on macroscopic appearances, particularly the shape and color of the object, and partially its movements. Accordingly, it is a descriptive method, and endoscopic findings ("endoscopic diagnoses") use descriptive terms corresponding to the appearances of the lesions, not to their histological structure. Of course, occasionally the appearances are so characteristic that clinical diagnosis can be anticipated with reasonable certainty. In the majority of cases, however, the endoscopic appearance allows for several interpretations and the definite diagnosis must be established on the basis of further examinations - biopsy or others. The sum of the terms used in a method or discipline is called nomenclature. It is mandatory that the nomenclature be internationally unified and usable as a database for computer programs. This goal is met by the standardized OMED nomenclature elaborated by the Terminology Committee of the World Society of Gastrointestinal Endoscopy which is used in this text. It has been published in full in several publications. Zdroj anotace: Web obalkyknih.cz