The Lifecycle of Clusters in Galaxies
  We review many of the basic properties of star cluster systems, and focus in
particular on how they relate to their host galaxy properties and ambient
environment. The cluster mass and luminosity functions are well approximated by
power-laws of the form $Ndm \propto M^{\alpha}dm$, with $\alpha\sim-2$ over
most of the observable range. However, there is now clear evidence that both
become steeper at high masses/luminosities, with the value of the downward turn
dependent on environment. The host galaxy properties also appear to affect the
cluster formation efficiency ($\Gamma$ - i.e., the fraction of stars that form
in bound clusters), with higher star-formation rate density galaxies having
higher $\Gamma$ values. Within individual galaxies, there is evidence for
$\Gamma$ to vary by a factor of 3-4, likely following the molecular gas surface
density, in agreement with recent predictions. Finally, we discuss cluster
disruption and its effect on the observed properties of a population, focussing
on the age distribution of clusters. We briefly discuss the expectations of
theoretical and numerical studies, and also the observed distributions in a
number of galaxies. Most observational studies now find agreement with
theoretical expectations, namely nearly a constant cluster age distribution for
ages up to ~100 Myr (i.e. little disruption), and a drastic steepening above
this value caused by a combination of cluster disruption and incompleteness.
Rapid cluster disruption for clusters with ages < 100 Myr is ruled out for most
galaxies.
