Crust is the outer part of a pie.
Crust is completely useless today. It may be beautiful with patterns and glazing and all. Still, without loads of lard or other fats that are considered bad for you today, crust is not worth eating since it is tasteless. Add all the sugar you want and you get sugary tastelessness. Try to feed your dog your pie crust and it will either ignore you for hours or bite you. Further, leave a few pieces lying around and it actually repels ants. The Mayo Clinic is experimenting with using pie crust in surgical procedures, since bacteria won't touch the stuff either.