Short answers, pulled from the story.
Publishing is the process of making information, literature, music, software, and other material available to the public in physical or digital form, for sale or free of charge. It traditionally covered printed works like books, comic books, newspapers, and magazines, and has expanded to include e-books, digital magazines, websites, social media, music, and video game publishing.
The Big Five publishing houses are Penguin Random House, Hachette, HarperCollins, Simon & Schuster, and Macmillan. They controlled about 80 percent of the United States trade market for books.
On the 2nd of November 2021, the United States Department of Justice filed a lawsuit to block the merger on antitrust grounds. On the 31st of October 2022, the D.C. District Court ruled in favor of the Department of Justice and filed a permanent injunction on the merger.
The Chinese inventor Bi Sheng made a movable type of earthenware around 1045, though no examples survive. The Korean civil servant Ch'oe Yun-ŭi invented the first metal movable type between 1234 and 1250 AD, and Johannes Gutenberg developed movable type in Europe around 1450.
A vanity press will publish any book, with the author covering all costs, surrendering some rights, and paying royalties on sales. A hybrid publisher shares the costs and risks of publication with the author, and because of that financial risk it is selective about what it publishes.
Privishing means publishing a book but printing so few copies, or with such lack of marketing and sales support, that it effectively never reaches the public. A book treated this way may be referred to as killed, and depending on the motivation it may constitute a breach of contract, censorship, or good business practice.