  We discuss various scattering mechanisms for Dirac fermions in single-layer
graphene. It is shown that scattering on a short-range potential (due to, for
example, neutral impurities) is mostly irrelevant for electronic quality of
graphene, which is likely to be controlled by charged impurities and ripples
(microscopic corrugations of a graphene sheet). The latter are an inherent
feature of graphene due to its two-dimensional nature and can also be an
important factor in defining the electron mean free path. We show that certain
types of ripples create a long-range scattering potential, similar to Coulomb
scatterers, and result in charge-carrier mobility practically independent on
carrier concentration, in agreement with experimental observations.
