  Magnetic fields are regarded as a crucial element for our understanding of
stellar physics. They can be studied with a variety of methods which provide
complementary - and sometimes contradictory - information about the structure,
strength and dynamics of the magnetic field and its role in the evolution of
stars. Stellar magnetic fields can be investigated either with direct methods
based on the Zeeman effect or through the observation of activity phenomena
resulting from the interaction of the field with the stellar atmosphere. In
this Cool Stars XVII Splinter Session we discussed the results obtained by the
many ongoing studies of stellar activity and direct studies of surface magnetic
fields, as well as the state- of-the-art techniques on which they are based. We
show the strengths and limitations of the various approaches currently used and
to point out their evolution as well as the interest of coupling various
magnetism and activity proxies.
