The early 19th century saw numerous improvements in the printing, publishing and book-distribution processes, with the introduction of steam-powered printing presses, pulp mills, automatic type setting, and a network of railways. These innovations enabled the likes of Simms and McIntyre of Belfast, Routledge & Sons (founded in 1836) and Ward & Lock (founded in 1854) to mass-produce cheap uniform yellowback or paperback editions of existing works, and distribute and sell them across the British Isles, principally via the ubiquitous W H Smith & Sons newsagent found at most urban British railway stations. These paper bound volumes were offered for sale at a fraction of the historic cost of a book, and were of a smaller format, 110 mm × 178 mm (4.3 in × 7.0 in), aimed at the railway traveller. The Routledge's Railway Library series of paperbacks remained in print until 1898, and offered the traveling public 1,277 unique titles.
The German-language market also supported examples of cheap paper-bound books:
Bernhard Tauchnitz started the Collection of British and American Authors in 1841. These inexpensive, paperbound editions, a direct precursor to mass-market paperbacks, eventually ran to over 5,000 volumes. Reclam published Shakespeare in this format from October 1857 and went on to pioneer the mass-market paper-bound Universal-Bibliothek series from 10 November 1867.
The German publisher Albatross Books revised the 20th-century mass-market paperback format in 1931, but the approach of World War II cut the experiment short. It proved an immediate financial success in the United Kingdom in 1935 when Penguin Books adopted many of Albatross' innovations, including a conspicuous logo and color-coded covers for different genres. British publisher Allen Lane invested his own financial capital to launch the Penguin Books imprint in 1935, initiating the paperback revolution in the English-language book-market by releasing ten reprint titles. The first released book on Penguin's 1935 list was André Maurois' Ariel.
Lane intended to produce inexpensive books. He purchased paperback rights from publishers, ordered large print runs (such as 20,000 copies—large for the time) to keep unit prices low, and looked to non-traditional book-selling retail locations. Booksellers were initially reluctant to buy his books, but when Woolworths placed a large order, the books sold extremely well. After that initial success, booksellers showed more willingness to stock paperbacks, and the name "Penguin" became closely associated with the word "paperback".
In 1939, Robert de Graaf issued a similar line in the United States, partnering with Simon & Schuster to create the Pocket Books label. The term "pocket book" became synonymous with paperback in English-speaking North America. In French, the term livre de poche was used and is still in use today. De Graaf, like Lane, negotiated paperback rights from other publishers, and produced many runs. His practices contrasted with those of Lane by his adoption of illustrated covers aimed at the North American market. To reach an even broader market than Lane, he used distribution networks of newspapers and magazines, which had a lengthy history of being aimed (in format and distribution) at mass audiences.
Because of its number-one position in what became a very long list of pocket editions, James Hilton's Lost Horizon is often cited as the first American paperback book. However, the first mass-market, pocket-sized, paperback book printed in the US was an edition of Pearl Buck's The Good Earth, produced by Pocket Books as a proof-of-concept in late 1938, and sold in New York City. In World War II, the U.S. military distributed some 122 million "Armed Services Editions" paperback novels to the troops, which helped popularize the format after the war.
Through the circulation of the paperback in kiosks and bookstores, scientific and intellectual knowledge was able to reach the masses. This occurred at the same time that the masses were starting to attend university, leading to the student revolts of 1968 prompting open access to knowledge. The paperback book meant that more people were able to openly and easily access knowledge and this led to people wanting more and more of it. This accessibility posed a threat to the wealthy by imposing that it would be turned upside down, as the masses were now able to access almost all of the knowledge the wealthy previously had access to. Treating the paperback as any other book drastically weakened the distinction between high and low culture. The paperback revolution essentially broke this relationship by redefining it through access to knowledge.