The American comic book as a print format was standardized in the mid-1930s — the saddle-stitched, roughly 7×10 inch pamphlet that became the delivery mechanism for Superman (1938), Batman (1939), and the superhero genre that followed. The visual conventions were shaped by economics as much as aesthetics: cheap newsprint required bold outlines and flat color; four-color printing technology determined the available palette; the page rate paid to artists rewarded speed over finish.

The result was a visual system with specific properties: the gutters between panels as a cognitive device asking readers to infer what happened between frames; the caption box as a narrative layer separate from dialogue; the visual grammar of motion lines, impact effects, and the distinctive sound-effect typography that rendered noise as letterform.

The Silver Age (mid-1950s to early 1970s) codified the aesthetic. Jack Kirby's dynamic diagonal compositions and "Kirby Krackle" (a pattern of small circles suggesting cosmic energy), Stan Lee's conversational caption style, and the specific Ben-Day dot texture of offset printing on newsprint all converged into what most people picture when they think "comic book."