https://en.wikipedia.org/wiki/Pulp_magazine

Pulp magazines (also referred to as "the pulps") were inexpensive fiction magazines that were published from 1896 until around 1955. The term "pulp" derives from the cheap wood pulp paper on which the magazines were printed. In contrast, magazines printed on higher-quality paper were called "glossies" or "slicks". The typical pulp magazine had 128 pages;[1] it was 7 inches (18 cm) wide by 10 inches (25 cm) high, and 0.5 inches (1.3 cm) thick, with ragged, untrimmed edges. Pulps were the successors to the penny dreadfuls, dime novels, and short-fiction magazines of the 19th century.

Although many respected writers wrote for pulps, the magazines were best known for their lurid, exploitative, and sensational subject matter, even though this was but a small part of what existed in the pulps. Digest magazines and men's adventure magazines were also regarded as pulps. Modern superhero comic books are sometimes considered descendants of "hero pulps"; pulp magazines often featured illustrated novel-length stories of heroic characters, such as Flash Gordon, The Shadow, Doc Savage, and The Phantom Detective.

The pulps gave rise to the term pulp fiction in reference to run-of-the-mill, low-quality literature. Successors of pulps include paperback books, such as hardboiled detective stories and erotic fiction.[2][3][4]