Doppler ultrasound is a medical imaging technique that uses sound waves to create images of blood flow in the body. It works by emitting high-frequency sound waves that bounce off moving objects, such as red blood cells. The device then analyzes the changes in frequency of the reflected sound waves to measure the speed and direction of blood flow. This technology is commonly used to assess conditions related to the heart and blood vessels, such as blood clots, heart valve issues, and arterial blockages. It is non-invasive, painless, and provides real-time information, making it a valuable tool in diagnosing and monitoring various health conditions.