Type Ia supernova progenitors: what do we know and what not?

Type Ia supernovae are by no means rare, which together with the
strong evidence that at least one white dwarf is involved, implies
that their progenitors should be fairly common too. Yet it is still
unclear what these are. There has been great progress in several
observational aspects of this issue. In addition the traditional
division between "single" and "double" degenerate models has been
challenged or at least complicated by a flurry of new possible
progenitor models. I will give an overview of these developments and
focus on the implications for our understanding of binary
evolution. Finally I will use this to discuss other compact binary
populations in the context of Gaia and as gravitational wave sources.