Nondestructive testing (NDT) is of major industrial interest for insuring safety and reliability of complex structures (nuclear plants, aircrafts, pipe-lines…). Among the various NDT methods used, techniques relying on the use of elastic waves at ultrasonic frequencies are the only ones which allow inspecting the whole volume of thick components; therefore, they are routinely used. The main NDT ultrasonic techniques make use of either bulk or guided waves. This mature technology is however still subject of intensive Researches and Developments (R&D) over a broad range from academic works to practical applications, to meet the growing needs from industry. French R&D in this field is at the highest level thanks to the strong needs emanating from its nuclear and aircraft industries which possess their own R&D teams working in close relation with academic laboratories, and the transfer of fundamental results to practical use is very efficient. There is a necessity for training engineers and researchers in this science to meet the numerous needs expressed.