In 1993, McCloud published the book Understanding Comics, a 215-page comic book about comics that explains the inner workings of the medium and examines the visual aspects of communication, including closure, symbolism, and iconography. The book is extremely popular among artists and the general public alike, and it is published in 15 languages. In 2000, he published the books more controversial sequel, Reinventing Comics. The 242-page book proposes 12 changes to the creation and distribution of comics, specifically advocating the expansion of online comics. The book's controversy rises from this idea of Web comics, and the debate among graphic artists has grown heated since the book's publication. Reinventing Comics is McCloud's only book that has been described as "dangerous."
McCloud is perhaps most well known for his first comic Zot!, which ran for 36 issues in California's Eclipse Comics. Zot! is a standard superhero story, but McCloud describes it as having "an alternative flavor" and "some unorthodox storytelling and compositions." McCloud sums up the plot as "a cross between Peter Pan, Buck Rogers and Marshall McLuhan." The comic ran from 1984-1991, during which time McCloud dabbled in several other small comic projects, including 1985's Destroy!!, and a 12 issue stint writing for Superman Adventures. In the mid 1990s, he published a graphic novel about Abraham Lincoln, which he reports to be "bizarre" and "generally disliked." In 1998, he published his first online comic, an adaptation of a Robert Browning poem entitled Porphyria's Lover. He has been publishing online comics ever since, including My Obsession with Chess, Carl Stories, Zot! Online: Hearts and Minds, I Can't Stop Thinking! (comic essays on comic technology), The Morning Improv (a comic illustrating a daily hour of Scott's brainstorms), and The Right Number, which is being released as a three-part graphic novella.
Throughout his career, McCloud has invented several tools for the creation and analysis of graphic art, including his 1988 Creator's Bill of Rights, the random story-generating beta program The Story Machine, and the 24-Hour Comic, a concept developed in 1990 after McCloud and fellow cartoonist Steve Bissette mutually challenged one another to create a 24-page comic in 24 consecutive hours. The idea was meant to compel creative output with a minimum of self-restraining contemplation. His most well-known invention in the comic world is The Big Triangle, which appears in his book Understanding Comics, and illustrates the spatial relationship between pictures, language, and icons in comics.