What is a 3D model? Also, in which way is this information transforming research in archaeology? This chapter will address the theoretical and methodological implications of introducing the third dimension in support of archaeological thinking. By using examples from different case studies, this chapter will review and discuss the implications of using 3D models for archaeological knowledge-making. This chapter presents an overview of the different types of 3D models which are mostly used to simulate various representations of archaeological records. It provides a discussion concerning limits and potentials of different types of 3D representations within the framework of archaeological practice, concluding that for a complete geometrical description of archaeological investigation environments, it is necessary to include as many types of 3D models as possible, as each of them represent an approximation of reality.