Letterforms, and the making of pages
Two adjacent colours will not line up perfectly, not on any press ever built. Trapping is deciding in advance which one loses, and rich black is the same decision made about the darkest thing on the page.
Three words for nearly the same thing, and the small differences that still matter at the bindery. One of them gave this software its name, which seemed worth explaining.
Four inks, four passes, and one of them a hair out of place. Everything you know about print colour — trapping, rich black, the fear of hairline type in three colours — follows from that single millimetre.
A palette is two decisions: what the ink is, and what it sits on. Everything else is adjustment, which is why one hex value can read warm on a cream page and dirty on a white one.
Three controls, three different jobs, and a great deal of type ruined by reaching for the wrong one. Kerning fixes a pair, tracking colours a paragraph, and letter-spacing is what you do to small caps and to nothing else.