In July 1934, Max Gaines and Eastern Color Printing published Famous Funnies, the first comic strip reprint omnibus in what would become the standard comic book format and so the start point for what has been traditionally called the Golden Age of Comics. The first use of the term is attributed to science fiction author Richard A. Lupoff from his article “Re-Birth” in the first issue of the fanzine Comics Art in 1961.

The Golden Age has no defining endpoint and is sometimes said to be followed by an interregnum period ending with the Silver Age of Comics, traditionally marked by the appearance of the revised Flash in DC’s Showcase #4 (Oct. 1956). According to Michael Uslan, the term originates from a 1966 fan letter in Justice League of America, but the Silver Age division is somewhat arbitrary since it applies only to DC Comics, which was already publishing nine superhero titles in 1956 featuring Superman, Batman, and Wonder Woman. The new character Batwoman also appeared three months earlier. The new Flash title, however, eventually led to DC’s 1959 Green Lantern in Showcase #22 and the Justice League of America in the 1960 Brave and the Bold #28, which in turn influenced Charlton Comics and Marvel Comics. Though initiated by DC, the Silver Age is most defined by the early 60s superhero comics of Stan Lee, Jack Kirby, and Steve Ditko published by Martin Goodman’s newly rechristened Marvel Comics, previously known as Atlas in the 50s and Timely in the 40s. From 1961-4 the company introduced the Fantastic Four, the Hulk, Spider-Man, Thor, Iron Man, the Avengers, the X-Men, Doctor Strange, and Daredevil.

Though less defined, the division between the Silver Age and the Bronze Age of Comics is understood largely as a tonal shift, as reflected by Dennis O’Neal’s relatively realistic scripting of Green Lantern Co-Starring Green Arrow beginning in 1970 and by the death of Gwen Stacy in Amazing Spider-Man #121 (July 1973). The Bronze Age also marks an artistic shift. Jack Kirby left Marvel in 1970, and Steve Ditko in 1966, allowing new artists Neal Adams and Jim Steranko to redefine the dominant style. The creative changes may also be understood as a response to a significant market slump, similar to the slump that endangered comics in the mid-50s and led to the resurgence of the superhero genre.

The Bronze Age is most often said to end when DC’s 1985 Crisis on Infinite Earths restructured the multiverse it unintentionally created with the 1956 Flash, while the 1986 publications of Frank Miller’s Batman: The Dark Knight Returns and Alan Moore and Dave Gibbons’ Watchmen mark a further creative shift to what is variously referred to as the Dark Age, Iron Age, or Modern Age, which either extends to the present or is divided in the late 90s when the darker themes emphasized by Moore and Miller ebbed.

In contrast to the ambiguity and competing interpretations of the comics Ages, the Comics Code Authority provides an objective means for dividing superhero comics into historical periods. The Code was created and managed by comic book publishers in an immediate response the 1954 Senate subcommittee hearings on the role of comic books in juvenile delinquency. The pre-Code era then runs from 1934, with the format-defining publication of Famous Funnies, to 1954. Since the Code was revised twice, the first Code era spans 1954 to 1971, the second 1971 to 1989, and the third begins in 1989. Marvel replaced the Code in 2000 with their own rating system, and DC stopped printing the Code stamp on their covers after their 2011 company-wide reboot—formally marking the start of the current, post-Code era. The third Code era is a transitional one, defined by less restrictive guidelines than those of 1954-1989 and a rise of comic books published without Code approval.

Mapping the two historical systems overtop each other, the pre-Code era and the Golden Age and all but the last two years of the interregnum correspond. The first Code era begins two years prior to the Silver Age, ending with the second Code era in 1971, also a common start point for the Bronze Age. The second Code then extends four years into the Modern Age before establishing clear divisions with the third Code and current post-Code eras.