Ultrasound uses high frequency sound waves to create images of internal organs and structures. It has several medical applications such as visualizing soft tissues, assessing blood vessels, and guiding procedures. The document discusses how ultrasound works, including how sound waves are produced and reflected to form images, and factors that affect image quality such as frequency, attenuation, and gain. Ultrasound is a valuable medical imaging tool when used by an operator with the proper knowledge and skills to acquire and interpret the images.