Theoretical models for bipolar flows are discussed with particular emphasis on new observational developments over the last year that have added significant constraints and understanding.
Implications of these flows for the cloud environment in which they are embedded are outlined. Associated objects such as masers and Herbig-Haro objects are analysed. It is shown that all
reasonable axisymmetic magnetohydrodynamic flows have some collimation along the symmetry axis. Observational tests of the theories are proposed. A connection between H2O masers and
protoplanetary systems in molecular disks is put forward.