  Stellar magnetism, explorable via polarimetry, is a crucial driver of
activity, ionization, photodissociation, chemistry and winds in stellar
environments. Thus it has an important impact on the atmospheres and
magnetospheres of surrounding planets. Modeling of stellar magnetic fields and
their winds is extremely challenging, both from the observational and the
theoretical points of view, and only recent ground breaking advances in
observational instrumentation - as were discussed during this Symposium - and a
deeper theoretical understanding of magnetohydrodynamic processes in stars
enable us to model stellar magnetic fields and winds and the resulting
influence on surrounding planets in more and more detail. We have initiated a
national and international research network (NFN): 'Pathways to Habitability -
From Disks to Active Stars, Planets to Life', to address questions on the
formation and habitability of environments in young, active stellar/planetary
systems. In this contribution we discuss the work we are carrying out within
this project and focus on how stellar magnetic fields, their winds and the
relation to stellar rotation can be assessed observationally with relevant
techniques such as Zeeman Doppler Imaging (ZDI), field extrapolation and wind
simulations.
