  Mass loss on the Asymptotic Giant Branch provides the origin of planetary
nebulae. This paper reviews several relevant aspects of AGB evolution:
pulsation properties, mass loss formalisms and time variable mass loss,
evidence for asymmetries on the AGB, binarity, ISM interaction, and mass loss
at low metallicity. There is growing evidence that mass loss on the AGB is
already asymmetric, but with spherically symmetric velocity fields. The origin
of the rings may be in pulsational instabilities causing mass-loss variations
on time scales of centuries.
