We begin by discussing the theory of transducers, the piezoelectric effect, and basic ultrasound transducer design. We then discuss basic beam characteristics and the evolution of transducers. In this module, we review the evolution of transducer development in a unique manner. Instead of just listing characteristics of each transducer type, we will focus on the benefits and limitations of each transducer type so that we can understand the motivation for designing each successive generation of transducers. There are two very evident benefits from this approach. First, this approach puts each successive generation of transducer into historical perspective and into context as to why each generation came into existence. Second, this approach teaches transducers from the perspective of the advantages and disadvantages of each transducer type, which happens to form the foundation of many of the exam questions related to transducers.