The world of materials is an exciting and challenging field of research since it has always played a dominant role in the evolution of human civilization. The demands from aerospace, defence, automotive and industrial branches on more advanced and innovative materials has led to the development of a new generation of materials with much better performance and capabilities than the existing conventional structural and functional materials. As a result, the era of smart materials has started. Smart materials can change their physical properties in response to a specific stimulus input. However, there is still a blurry image over the types and potential applications of smart materials. The objective of this paper is to define the field of smart materials and structures, together with its current status and potential benefits. However, more focus will be devoted to piezoelectric materials and results are presented and discussed. Finally, and in order to demonstrate the characteristics of one class of smart materials, two numerical examples are proposed and results are presented.