  We give a survey of the approaches to classifying foliations, starting with
the Haefliger classifying spaces and the various results and examples about the
secondary classes of foliations. Various dynamical properties of foliations are
introduced and discussed, including expansion rate, local entropy, and orbit
growth rates. This leads to a decomposition of the foliated space into Borel or
measurable components with these various dynamical types. The dynamical
structure is compared with the classification via secondary classes.
