  Globular clusters provide a unique probe of galaxy formation and evolution.
Here I briefly summarize the known observational properties of globular cluster
systems. One re-occurring theme is that the globular cluster systems of spirals
and ellipticals are remarkably similar. Photometry, and the limited spectra
available, are consistent with metal-poor clusters forming before the main
spheroid component is established and the metal-rich ones forming at the same
time as the spheroid in a burst of star formation. These observations are
compared to a model for globular cluster formation in a LCDM hierarchical
universe. One model result reported here is that S_N is determined at early
times and little affected by late epoch mergers.
