Alternative versions of Superman establish a new continuity for DC, affecting not only Superman, but all of the DC Comics characters. The versions of Superman from this time period are traditionally divided into three main periods. The first version of Superman began being published by DC Comics in 1938 appearing in "Action Comics" #1. To explain discrepancies in the aging of Superman across several decades, his earliest stories were retroactively portrayed as having taken place on an alternative world called Earth-Two. These stories take place from 1938 until the late 1950s, although the exact dividing line is unclear and some stories happened identically to
Superman as editor of the Superman comics. In the earlier decades of Superman comics, artists were expected to conform to a certain "house style". Joe Shuster defined the aesthetic style of Superman in the 1940s. After Shuster left National, Wayne Boring succeeded him as the principal artist on Superman comic books. He redrew Superman taller and more detailed. Around 1955, Curt Swan in turn succeeded Boring. The 1980s saw a boom in the diversity of comic book art and now there is no single "house style" in Superman comics. The first adaptation of Superman beyond comic books was a radio show,