In the last two decades, ultrasound (US) application in food processing, preservation, and extraction increased exponentially. Its positive impacts have been investigated and proved in thousands of scientific publications. This technology can be used to enhance some food processes such as drying, cooking, emulsification, and degassing. It was also reported to provide an efficient inactivation of microorganisms and enzymes, particularly when combined with heat and/or pressure. Moreover, US-assisted extraction (UAE) is one of the most common applications of US in food industry. UAE presents several advantages compared to conventional extraction techniques such as the reduction of time and temperature as well as ensuring extracts of higher quality. This chapter provides a complete view of US technology in food processing. The first part aims to better understand the US theory and the parameters influencing its performances. The most common ultrasonic equipment are presented in the second part. The final part is dedicated to examples of US applications in food processing, preservation, and extraction.