The aim of this chapter is to constitute the dynamic figural register. In order to do this, and based on the theory of Registers of Semiotic Representation and on the pertinence of the use of a Dynamic Representation Environment (DRE) for geometry teaching and learning, I revisit the three cognitive activities essential to every semiotic representation in the sense of Duval, which I call dynamic formation, dynamic treatment, and dynamic conversion, because it may be noticed that, when a person interacts with DRE, the three cognitive activities possess different features than when using pencil and paper.