Per the Encyclopaedia Britannica, a graphic novel is defined as "a type of text combining words and images", and more specifically as "a long comic narrative for a mature audience, published in hardback or paperback [...] with serious literary themes and sophisticated artwork."
Yet even that definition is up to some debate and further clarification, as just as many graphic novels today are published for child and teen audiences, with many such examples in recent years winning noteworthy literary prizes and even being adapted into feature-length movies or television series. In addition, many books that are sold as "graphic novels" were not initially intended to be novels, but instead present stories that were originally published in serialized installments over the course of several comic book issues.
In a way, it is fitting that so many graphic novels and other comics, for audiences of all ages, find their way to the screen. Much like a film, a graphic novel is an art form that functions as a visual narrative — the underlying visual design and structure, and the details in each panel and page, are just as important as the story which plays out over the course of the novel. In short, the graphic novel must be seen as well as read.
Like a single frame or series of frames in a movie, each individual comics panel or panel sequence is both a work of art which can be analyzed on its own and a piece of a larger whole. As an example, here we see perhaps the most famous opposing pair in all of comics, Batman and the Joker, facing off in this panel sequence from Batman: The Killing Joke (author: Alan Moore; illustrator: Brian Bolland; DC, 1988, p. 11).
Even these few panels, removed from the larger story, open up many intriguing artistic questions. What Batman is saying is important, since the dialogue moves the story forward, but what's being shown is equally important. For instance, what is the significance of:
Cartoon Art Museum, San Francisco
Kyoto International Manga Museum