Boasting outstanding merits, including excellent portability, real-time imaging performance, low cost, and broad accessibility, medical ultrasound has emerged as an indispensable imaging and therapeutic tool across global clinical settings, especially in resource-limited settings, in recent decades. This book introduces the main ultrasound imaging modalities and their applications in diagnosing breast, heart, and kidney lesions. This book also explores low-intensity therapeutic ultrasound technologies. In addition, the cutting-edge AI-driven ultrasound is introduced. This book can serve as a practical reference for radiologists, medical engineers, researchers, and graduate students engaged in medical ultrasound.