  The observed distribution of IMF shapes can be understood as statistical
sampling from a universal IMF and variations that result from stellar-dynamical
processes. However, young star clusters appear to have an IMF biased towards
low-mass stars when compared to the Galactic disk IMF, which comprises an
average populated by star-formation episodes occurring Gyrs ago. In addition to
this tentative but exciting deduction, this text outlines some of the stumbling
blocks hindering the production of rigorous IMF determinations, and discusses
the most robust evidence for structure in it. Also, it is stressed that an
invariant IMF should not be expected.
