The aim of the chapter is to highlight all the important clinical uses of ultrasound in anesthesia and critical care practice. Ultrasound is a point-of-care imaging modality that is being increasingly adopted in critical care practice and anesthesiology. Ultrasound is a mechanical wave that requires a medium to travel (e.g., human tissue), it has acoustic frequency that is above the threshold for human hearing (20 kHz). Ultrasound is now considered as a standard in central venous cannulation and peripheral nerve block. Apart from providing precision in these procedures, ultrasound has now emerged as an essential bedside monitor to diagnose, assess, and treat life-threatening conditions without delay. It helps to delineate type of shock and offers immediate assessment of all vital organs using focused echocardiography, lung and abdominal ultrasound in addition to transcranial doppler with optic sheath diameter assessment. Ultrasound is also being used to assess the airway and patients’ fasting status by measuring antral diameter.