An American comic book is a small magazine originating in the United States and containing a narrative in the form of comics. Since 1975 the dimensions have standardized at 17 x 26 cm (6 ⅝" × 10 ¼"), although larger formats appeared in the past.

Since the invention of the comic-book format in 1934, the United States has produced the most examples, with only the British comic books (during the inter-war period and up until the 1970s) and the Japanese manga as close competitors in terms of quantity.

Sales of comic books began to decline after World War II, when the medium had to face competition with the spread of television and mass-market paperback books. Confirming the trend, mass-media researchers in the period found comic-book reading among children with television sets in homes "drastically reduced". In the 1960s, comic books' audience expanded to include college students who favored the naturalistic, "superheroes in the real world" trend initiated by Stan Lee at Marvel Comics. The 1960s also saw the advent of the underground comics. Later, the recognition of the comic medium among academics, literary critics and art museums helped solidify comics as a serious artform with established traditions, stylistic conventions, and artistic evolution.