  Most of a star's mass is bound in a hydrostatic equilibrium in which pressure
balances gravity. But if at some near-surface layer additional outward forces
overcome gravity, this can transition to a supersonic, outflowing wind, with
the sonic point, where the outward force cancels gravity, marking the division
between hydrostatic atmosphere and wind outflow. This talk will review general
issues with such transonic initiation of a stellar wind outflow, and how this
helps set the wind mass loss rate. The main discussion contrasts the flow
initiation in four prominent classes of steady-state winds: (1) the
pressure-driven coronal wind of the sun and other cool stars; (2) line-driven
winds from OB stars; (3) a two-stage initiation model for the much denser winds
from Wolf-Rayet (WR) stars; and (4) the slow "overflow" mass loss from highly
evolved giant stars. A follow on discussion briefly reviews eruptive mass loss,
with particular focus on the giant eruption of eta Carinae.
