The design is drawn on a wood plank (side grain) and those areas that are not to print are cut away well below the surface with a knife or gouge. When inked, it is the uncut surface that takes the ink. Linocut is the same technique using linoleum rather than wood.
In all relief techniques it is the surface of the block that is inked and printed and, given perfect printing, all lines or surfaces will be equally dark. Moderate pressure in the press will emboss the paper to an extent, so the inked design will lie slightly below the uninked surface of the paper.