Abstract
Major results from recent observations of T Tauri stars are reviewed. These stars appear to be strongly concentrated along the convective tracks in the HR diagram. It is now well established that T Tauri stars are not only in the pre-main sequence phase but are actually in a pre-radiative equilibrium phase. The combined optical, IUE, and X-ray data lead to a picture of violent chromospheric activity which is strongly tied to the solar analogy. New measurements of stellar rotation are described and the angular momentum history of the stars is outlined. In conclusion, it is stated that T Tauri stars are probably past the dominantly infall phase associated with dynamical collapse and represent instead a transition phase to the normal photosphere, chromosphere, corona, and stellar wind stage.
