In 2016 the first edition of the SAGES Manual Operating through the Endoscope was published. At the time, this represented a review of cutting-edge new technologies that were being introduced within the field of flexible endoscopy. Largely based on applications and data up to 2013, this served as a unique resource for clinicians and researchers to learn about this expanding field. Since then, there has been a significant expansion of new technologies and procedures within this discipline that have meaningfully changed this entire sub-specialty. In addition, large numbers of high-quality data have emerged that support more heartily the safety and efficacy of these techniques. Major international societies now routinely include hands-on training and scientific content of this field in meetings and educational efforts, and many trainees and practitioners are looking for resources to improve their knowledge and technical skills sets. For these reasons, an update on this rapidly advancing field seems appropriate at this time, given the enormous amount of new content available. Endoscopic surgical procedures allow for less invasive access for performing increasingly complex procedures. This results in maximal benefit for patients with fewer complications, faster recovery, and less pain. Endoscopy allows access to the gastrointestinal tract without transgressing the abdominal or chest walls, by means of a truly less invasive route. These technologies and skills are being sought out by practitioners and asked for by patients. The proposed textbook is designed to present a comprehensive and state-of the-art approach to the diverse applications of surgical techniques and procedures through the endoscopic platform. Written by experts and emerging specialists in that field, each of these sections will address patient selection, pre-operative considerations, technical conduct of the most common operations, and avoiding complications. A review of the existing literature addressing the particular topic will follow in each section. Extensive endoscopic images and illustrations will make this an interactive text. In addition to updates on most topics in the previous manual, this edition will include exciting new fields of advanced imaging, artificial intelligence and augmented imaging, applications of robotics to endoscopy, and more robust exposure of endoscopic applications for treatment of obesity, a worldwide epidemic. The subject of surgical endoscopy has changed meaningfully since publication of the first edition; now a substantial focus of major journals, scientific meetings, and online platforms. A timely update can capture this broad subject in an accessible manual focused on technologies and data supporting these interventions.