  A survey of currently known planet-hosting stars indicates that approximately
25% of extrasolar planetary systems are within dual-star environments. Several
of these systems contain stellar companions on moderately close orbits,
implying that studies of the formation and dynamical evolution of giant and
terrestrial planets, in and around binary star systems have now found realistic
grounds. With the recent launch of the space telescope CoRoT, and the launch of
NASA's Kepler satellite in 2009, the number of such dynamically complex systems
will soon increase and many more of their diverse and interesting dynamical
characteristics will soon be discovered. It is therefore, both timely and
necessary, to obtain a deep understanding of the history and current status of
research on planets in binary star systems. This chapter will serve this
purpose by reviewing the models of the formation of giant and terrestrial
planets in dual-star environments, and by presenting results of the studies of
their dynamical evolution and habitability, as well as the mechanisms of
delivery of water and other volatiles to their terrestrial-class objects. In
this chapter, the reader is presented with a comprehensive, yet relatively less
technical approach to the study of planets in and around binary stars, and with
discussions on the differences between dynamical characteristics of these
systems and planetary systems around single stars.
