As the Sun emerges from a period of unprecedented low activity, the nature of the Sun's magnetic field compared to that of other stars is a particularly timely question. Just as observations of the full 3D structure of the solar magnetic field are becoming available through STEREO and SDO, advances in spectropolarimetric techniques now allow us to map the surface magnetic fields of other stars, revealing the great diversity of magnetic geometries that stars of different masses and rotation rates can display. This has now been possible for over 60 main sequence stars, with a smaller number of younger, pre-main sequence stars also mapped. Modelling of coronal structures based on these observations is revealing the full nature of stellar magnetic activity and its possible impact on orbiting planets.
