A large body of theoretical and computational work shows that jets - modelled
as magnetized disk winds - exert an external torque on their underlying disks
that can efficiently remove angular momentum and act as major drivers of disk
accretion. These predictions have recently been confirmed in direct HST
measurements of the jet rotation and angular momentum transport in low mass
protostellar systems. We review the theory of disc winds and show that their
physics is universal and scales to jets from both low and high mass star
forming regions. This explains the observed properties of outflows in massive
star forming regions, before the central massive star generates an ultracompact
HII region. We also discuss the recent numerical studies on the formation of
massive accretion disks and outflows through gravitational collapse, including
our own work on 3D Adaptive Mesh simulations (using the FLASH code) of the
hydromagnetic collapse of an initial rotating, and cooling Bonner-Ebert sphere.
Magnetized collapse gives rise to outflows. Our own simulations show that both
a jet-like disk wind on sub AU scales, and a larger scale molecular outflow
occur (Banerjee and Pudritz 2005).