Hot Type is the epic story of the magnificent 19th-century machine that rendered Gutenberg's movable type obsolete and opened the portal to the long century of mass media. The Linotype mechanized the 400-year-old process of setting type one laborious letter at a time, and thus ignited an explosion of newspaper, book, and magazine empires. The technology helped transform Mark Twain into a premier literary celebrity, but also cost him his fortune - as well as his sense of humor and optimism. The Linotype's era was a bridge between Twain's Gilded Age with its tycoons of steam, steel, and wire and today's Gilded Age with its barons of bits and AI. This is a tale populated with wondrous characters: tragic inventors, malign media moguls, hand-typesetters called the Swifts who turned their craft into a spectator sport, and authors and journalists who chronicled the turmoil of their time, their every word molded into metal type by what some viewed as a thinking machine. The Linotype would die at the hands of the computer, taking down with it printers' unions and many a newspaper. Its history provides an opportunity to examine the impact of technology on culture just as new technologies - the internet and artificial intelligence - manufacture their endless streams of words today.