Stellar systems, star clusters and globular clusters

The morphology, distribution, and evolution of star clusters are discussed in a general review of theoretical and observational investigations. Topics examined include stellar systems and the universe (the connection between stellar astrophysics and cosmology), Galactic clusters, globular clusters, the original He content and ages of globular clusters, the problem of the second parameter, gaps in the HR diagram, and extragalactic globular clusters. Graphs and diagrams are provided, and the opportunities offered by improvements in observational instrumentation are indicated.