This book focuses on thoracic ultrasound, a versatile, diagnostically accurate, low-cost, noninvasive and non-ionizing imaging technique. Thanks to portable devices, the method can be used to provide quick and accurate diagnoses in emergency settings, during transport, or at the patient’s bedside in intensive care units. In addition, as a dynamic examination that allows “real-time” assessment, it can be used to optimize diagnoses, the use of respiratory support equipment, surgical interventions and physiopathological assessments, both in critical patients and those with chronic conditions. Lastly, since it avoids ionizing radiation, thoracic ultrasound offers a first-line diagnostic tool for thoracic disease assessment in connection with pregnancy, neonatology and pediatrics.