organs - who what when why?

 I saw this organ today at a thrift shop and thought of LA's organ photo collection - which is surprisingly attractive to me despite that organs generally remind me of really ugly ceder paneled basements in houses that smell like onions. I don't really get how these things work (why are there 2 rows of keys?) or if their played anywhere but in church (if that). I also don't get why so many people bought these things instead of pianos. Who started this big organ craze that has left thrift stores permanently stocked? I'm guessing some kind of love of church music and polka. Is there an organ graveyard somewhere? I can't imagine anyone wanting to own one. Am I wrong? So many questions...

Anyway, LA, this one's for your collection.
You'd better watch out.
One day, you're going to start finding them on your front door step.
These things have a habit of being 'given' away to those who show even a hint of interest...

love Jill