  We review star formation in molecular clouds and describe why magnetic fields
may be important and how they can influence filamentary structure and the
column density probability distribution function (PDF). We also comment on the
origin of the stellar and substellar initial mass function (IMF), which may
require explanations beyond a simple Jeans length argument in turbulent
molecular clouds. A mathematical model of the modified lognormal power-law
(MLP) distribution function provides a framework within which to connect
accretion processes with the IMF.
