Galactic chemical evolution: the observational side
  In this review I outline some ideas in chemical evolution, necessary for
understanding the evolution of galaxies from measured elemental abundance
ratios. I then discuss abundance results from studies of Local Group dwarf
galaxies and the globular cluster Omega Cen. I present a qualitative scenario
of prolonged chemical enrichment in a leaky box that can explain the observed
abundance ratios in these systems. Space limitations prevent a comprehensive
review of this vast field, so I have restricted the discussion to dwarf
systems.
