Until about a decade ago, star clusters were considered "simple" stellar populations: all stars in a
cluster were thought to have similar ages and the same metallicity. Only the individual stellar masses
were thought to vary, in essence conforming to a "universal" initial mass function. Over the past
decade, this situation has changed dramatically. I will discuss my group's recent progress in this
context, with particular emphasis on the properties and the alleged presence of multiple populations in
Local Group star clusters across the full age range. Our most recent results imply a reverse paradigm
shift, back to the old simple stellar population picture for at least some intermediate- age (~2
Gyr-old) star clusters, which opens up exciting avenues for future research efforts.
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