Bread crumb
The crumb is the interior of a loaf beneath the crust. It is judged on its cell structure — the size of the holes, how even they are, the shape of the walls — along with moisture and springiness to the touch.
An open crumb with large irregular holes comes from high-hydration dough handled gently: ciabatta, rustic sourdough. A fine even crumb comes from lower hydration and more intensive mixing, as in tin and sandwich loaves where a regular structure matters more.
The crumb reads as a report on the process. A dense damp band above the bottom crust points to underbaking; large voids under the top crust to slack shaping or over-proofing; uniformly small tight cells in a high-hydration dough to under-fermentation. Only judge structure once the loaf is fully cool — in warm bread the starch has not yet set.