This introduction chapter presents an overview of rotations in three dimensions, setting the context for the material covered in the text. An object’s position and orientation are both described informally, with later chapters detailing formally the respective mathematical fundamentals. The axis of rotation and its role in describing orientation is outlined. An important issue related to combining rotations is highlighted and the difference between active and passive rotations is explained. The topic of how to describe rotations, i.e. rotation parameterisation, is introduced followed by a historical perspective on key publications. The chapter ends with coverage of important details to be aware of when starting the study of rotations.