Why are ceilings always painted white?

And not even the same white as the rest of the room, if the room is indeed white? I was pondering this today after I saw that our bathroom got repainted!! Yahoo!! No more water spots on the walls from them not painting before we moved in!

Another movie quote, since I seem to be all about them today:

I'm just a girl, standing in front of a boy, asking him to love her. ~ Notting Hill.

I love that movie!