Devoted to simulation‎,‎ this issue offers insights on the evolution of simulation in GI endoscopy and comparative overviews of the current state of the use of simulation in the aviation industry‎,‎ driver‎'‎s tests‎,‎ and laparoscopic surgery‎.‎ All of the major available types of simulators‎-ex‎-vivo‎,‎ artificial tissue‎,‎ and the computer simulators ‎- will be described in detail‎,‎ with an emphasis on what specific skills can be taught using each type‎.‎ Also discussed are the optimal use of various simulators and models for EGD‎,‎ Colonoscopy‎,‎ ERCP‎,‎ EUS‎,‎ and hemostasis‎,‎ with a focus on evidence‎-based validation data where available‎.‎ Of great importance is the proper integration of various models at various stages of training and for different trainees‎;‎ also discussed are the logistical obstacles to more widespread utilization of simulators and a look to the future‎,‎ including the use of simulators for testing competency‎.‎This issue should be of great interest to students and teachers of endoscopy alike‎.‎ It should also interest non‎-gastroenterologists who perform endoscopic procedures and individuals involved in supervising physician education and credentialing‎.‎ The key words include‎:‎ simulators‎;‎ endoscopy‎;‎ colonoscopy‎;‎ ERCP‎,‎ EUS‎;‎ hemostasis‎;‎ virtual reality‎;‎ ex‎-vivo models‎;‎ competency‎;‎ training‎;‎ and credentialing‎.‎