nitty-gritty (
http://definr.com/nitty-gritty)
n : the choicest or most essential or most vital part of some
idea or experience: "the gist of the prosecutor's
argument"; "the heart and soul of the Republican Party";
"the nub of the story" [syn:
kernel,
substance,
core,
center,
essence,
gist,
heart,
heart and soul,
inwardness,
marrow,
meat,
nub,
pith,
sum]