  The possibility of measuring the internal rotation of the Sun and stars
thanks to helio- and asteroseismology offers tremendous constraints on hydro-
and magnetohydrodynamical processes acting in stellar interiors. Understanding
the processes responsible for the transport of angular momentum in stellar
interiors is crucial as they will also influence the transport of chemicals and
thus the evolution of stars. Here we present some of the key results obtained
in both fields and how detailed seismic analyses can provide stringent
constraints on the physics of angular momentum transport in the interior of low
mass stars and potentially rule out some candidates.
