What constitutes "affordable housing" and how are these homes financed
through banks? Whats the process?

Hi.  I'm not a reseacher, just a construction/property development guy.
Where exactly did you get the phrase "affordable housing"?  It could
mean quite a few things (such as being location driven, or Habitat for
Humanity, or grant-funded communities, or federal HUD rehab
projects)..  You might consider looking through the programs on the
federal HUD website.

I am really looking for a passable defination of "affordable housing"
and the process from start to finish in the development of these
sites. I want to understand how a bank defines "affordable" and how
they finance particular people who are looking for this.

I picked up that term from my college class where we're studying the
Growth Mangement Act (GMA) and land-use issues.

The term is somewhat flexible, but it's usually applied as follows:

A housing project sets aside X% of its capacity for people who make up
to Y% of local median income. The X and Y values can vary a lot
depending on who is mandating the "affordable housing" label.

The big GSEs (Fannie Mae, Freddie Mac) probably have more strict
guidelines, because they're required to devote some of their efforts
to promoting "affordable housing".