Also known as "whole rye", pumpernickel flour is a type of rye flour that is of a coarser grind then regular rye flour.  It is most commonly used to make pumpernickel bread which is very popular in Northern and Eastern European countries.  With its deep, hearty and distinctive flavor, it is considered the rye equivalent of whole wheat flour as it contains the bran, germ and endosperm of the rye berry.  Rye flour contains a high percentage of soluble fiber along with minerals such as manganese, phosphorous and selenium.  Due to its lower gluten content, breads made with mostly rye flour will not rise as much and the crumb will be more dense with smaller holes.