From Sonic Retro
A comic book is a magazine or book containing the art form of comics. Comic books are often called comics, especially in the United Kingdom. Although the term implies otherwise, the subject matter in comic books is not necessarily humorous. In fact, it varies widely.
Many early comic books were simply collections of comic strips 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 conventions specific to comic books like splash pages. Long-form comic books are called graphic novels.