  It is now clear that a binary pathway is responsible for a significant
fraction of planetary nebulae, and the continually increasing sample of known
central binaries means that we are now in a position to begin to use these
systems to further our understanding of binary evolution. Binary central stars
of planetary nebulae are key laboratories in understanding the formation
processes of a wide-range of astrophysical phenomena - a point well-illustrated
by the fact that the only known double-degenerate, super-Chandrasekhar mass
binary which will merge in less than a Hubble time is found inside a planetary
nebula. Here, I briefly outline our current understanding and avenues for
future investigation.
