Galaxies are not isolated and static "Island Universes." Material
flows into, within, and out of them via accretion and large-scale
fountains and outflows powered by intense star formation episodes
(starbursts) and nuclear activity driven by supermassive black holes
(AGN). I will summarize the current observational evidence for this
"galactic ecosystem" in and around nearby and distant galaxies. Then I
will look to the future and discuss how the new
radio/millimeter/sub-millimeter-wave facilities planned for the 2020s
and beyond should allow us to make significant progress in this area
of research.