Some people like to use the term graphic novel simply as a more sophisticated way to describe the format traditionally known as "comic books." The "real" definition of the term is often debated among those who use it, some refusing to use it at all. Additionally, the line between what is a graphic novel and what is a comic book are easily blurred by those who created the terms.
However, for the purposes of this guide, graphic novels should be considered sequential art narratives that are the equivalent in form to prose novels. Simply put, they have a beginning and an end, unlike comic books which run continuously with new storylines and issues printed for as long as the publisher allows.
Unfortunately, since the scholarly study of comics and graphic novels is fairly new, the terms used to describe said works are far from standardized. It is good to keep an open mind in one's research, searching for both the terms comic book and graphic novel whenever possible.