  Binary systems are very common among field stars. While this relatively small
number of planets in binaries is probably partly due to strong observational
biases, there is, however, statistical evidence that planets are indeed less
frequent in binaries with separations smaller than 100 au, strongly suggesting
that the presence of a close in companion star has an adverse effect on planet
formation. It is indeed possible for the gravitational pull of the second star
to affect all the different stages of planet formation, from proto-planetary
disk formation to dust accumulation into planetesimals, to the accretion of
these planetesimals into large planetary embryos and, eventually, the final
growth of these embryos into planets. For the crucial planetesimal accretion
phase, the complex coupling between dynamical perturbations from the binary and
friction due to gas in the protoplanetary disk suggests that planetesimal
accretion might be hampered due to increased, accretion hostile impact
velocities. Likewise, the interplay between the binary secular perturbations
and mean motion resonances lead to unstable regions, where not only planet
formation is inhibited, but where a massive body would be ejected from the
system on a hyperbolic orbit. The amplitude of these two main effects is
different for S and P type planets, so that a comparison between the two
populations might outline the influence of the companion star on the planet
formation process. Unfortunately, at present the two populations (circumstellar
or circumbinary) are not known equally well and different biases and
uncertainties prevent a quantitative comparison. We also highlight the long
term dynamical evolution of both S and P type systems and focus on how these
different evolutions influence the final architecture of planetary systems in
binaries.
