Abstract
In this chapter we provide an overview of tomographic techniques used to map the surfaces of single and binary stars. Brightness and magnetic field maps allow us to study surface activity, spot and magnetic field variability and map irradiation patterns on secondaries of cataclysmic variable systems (CVs). During the past few years, magnetic fields have been detected and studied on stars throughout the Hertzsprung-Russell diagram. Spectropolarimetric analyses using the technique of Zeeman Doppler Imaging have played a key role in this exploration. We briefly summarise the theoretical puzzles addressed in the field of stellar magnetic activity, discuss issues specific to spectropolarimetry and Zeeman Doppler Imaging, and present recent results. We also discuss how future instruments operating in the near infrared will contribute to the next advances, especially for M type dwarfs, brown dwarfs and young stars.