Scott McCloud is a comic book writer & artist who experienced some minor fame & success with runs on various comics & with his own creation ZOT!, in 1993, McCloud decided to break out of fiction & try to theorize the confusing & misunderstood comic book. Understanding Comics: The Invisible Art was his graphic novel where he defined the comic & its vocabulary, gave its history & theorized the various elements of the comic & their uses. It was a groundbreaking graphic novel because it was comic theory in comic form. Most comic theory books before this were text-based, but McCloud wanted to emphasize the power of the medium.
This graphic novel does have its controversy, especially when McCloud defines the comic & what he considers art. His definition of art includes "any human activity that doesn't grow out of our species' two basic instincts: survival & reproduction." This definition opens a whole can of worms that many will find engrossing. Still, McCloud realizes that he theories are just that & hopes that this novel will open up a debate.