Pulp magazines are so-called because of the cheap paper they were printed on. Frank A. Munsey pioneered the format in 1896 with Argosy. Pulps picked up steam with titles like Blue Book (1906) and Adventure (1910), then exploded in 1912 when All-Story printed a little story by Edgar Rice Burroughs called "Tarzan, the Ape-Man." Soon after, genre titles flourished, like Detective Story, Western Story, and Love Story; Then in the Twenties publishing legends like Black Mask (1920), Weird Tales (1923) and Amazing Stories (1926) took hold.

In 1931, Street & Smith was promoting Detective Story by having stories read on the radio. This narrator called himself "The Shadow" and S&S were quick to jump on this memorable name that had eclipsed the title of the magazine he was promoting. Within a few years The Shadow had started a whole rush of "Hero Pulps" including Phantom Detective, Doc Savage, Nick Carter, G-8 and His Battle Aces, and The Spider. In the early Thirties, before Radio really had its heyday, Pulps were the dominant entertainment, like television is today.

After World War II, the demand for Pulp magazines waned, as a more durable cheap entertainment took hold: paperbacks. (These were often just as "Pulpy" since they were being written by a lot of the same authors.) In the fifties, television became the dominant form of escapism and the surviving Pulps finally ceased publication. Fiction magazines continued to be published of course, but these sf and mystery digests, and "men's magazines," aren't considered Pulps.

Pulp Collecting
I read a lot of Doc Savage and Spider stories before I ever laid eyes on an actual Pulp magazine. If you're ready to move beyond the reprints, here's my take -- plus some helpful links.

Pulp Preservation
Some advice on the care and feeding of Pulp magazines, based on my own reading and experience.