In recent years, nasal high-flow therapy (NHF) has established itself as a new form of non-invasive respiratory support and oxygenation. Initially met with skepticism, large landmark studies have demonstrated its benefits in clinical practice. Excellent physiological studies have enhanced the understanding of how NHF works, and the ongoing enthusiasm for the method has led to rapidly growing research activity. Notably, many observational studies and retrospective surveys also indicate positive effects on breathing and outcomes in the context of the COVID-19 pandemic. Pioneering authors have contributed to the creation of this volume, which presents the knowledge of NHF for the first time in a consolidated manner. It aims to facilitate a quicker understanding and increasing acceptance of nasal high-flow therapy among colleagues, researchers, and interested parties alike.