Abstract. Classical T Tauri stars offer an excellent laboratory to study the accretion process and star-disk interaction, which define the transfer of mass and angular momentum in the system. The interaction takes place very close to the star, in a region of about a few stellar radii, and it is therefore challenging to study in detail the physics of the magnetosphere in young stellar objects. We will discuss, through observational examples, how our description of a static and axisymmetric stellar magnetosphere from the early 90s has evolved to a very dynamical multipolar region that takes into account non-steady accretion and time-dependent star-disk interactions.