A comic book -- or comic for short -- is a magazine or book containing sequential art in the form of a narrative. Although the term implies otherwise, the subject matter in comic books is not necessarily humorous; in fact, it is often serious and action-oriented. Comic books are so called because some of the earliest comic books were simply collections of comic strips (most of which were humorous) that had originally been printed in newspapers. The commercial success of these collections led to work being created specifically for the comic book form, which fostered specific conventions such as splash pages.

Long-form comic books, generally with hardcover or trade-paper binding came to be known as graphic novels, but the term's definition is vague. Like jazz music (and a handful of other cultural artifacts), comic books are a rare example of an indigenous American art form though prototypical examples of the form exist.

American comic books have become closely associated with the superhero tradition. In the United Kingdom, the term comic book is used to refer to American comic books by their readers and collectors, while the general populace would likely consider a comic book a hardcover book collecting comics stories. The analogous term in the UK is a comic, short for comic paper or comic magazine.