Protostars and planets: overview from an astronomical perspective.

Current problems in understanding the formation and early evolution of stars are reviewed. First discussed are observational studies of external galaxies which may provide insight into the factors controlling star-forming efficiency and the initial mass function. Advances in the classification of molecular cloud properties in the Milky Way are summarized. Considerable emphasis is given to a discussion of recent observations of mass outflows from young stellar objects and the possibility that such outflows may provide a guide to the role played by magnetic fields during the prestellar collapse phases. Recent observations of possible disk structures surrounding young stellar objects are presented along with a picture of one such disk, that surrounding the T Tauri star, HL Tau.