The first recorded published comic was a political cartoon that Benjamin Franklin created in 1754. It wasn't until the 1920s that companies published actual comic books that were available on newsstands. Many of these comics were reprints of newspaper comics. Publishing companies like National Allied Publications, later called DC Comics, catered to the wants of the public and published original detective and humor comics. These companies formed the heart of traditional comic book publishing.
Traditional comic book publishing requires a finished product. The comic book itself must be written and drawn and a final draft created before you can set out for traditional publishing venues. The only caveat to this is if you are selling an idea to an established comic book company such as DC or Marvel. They will purchase the rights to the story and either hire you to develop it or do it in house.
Traditional comic book publishing requires an actual physical comic book versus a comic book published on a website. Small comic book publishing companies hire printing companies to print their comics because the costs of their own printing press, ink and paper are too high. The company must decide on how many copies to print on the first run as well as the quality of the paper and vibrancy of the colors.
Traditional comic book publishing is done through distributors to comic book stores and even some major department stores. Smaller traditional publishers will visit the comic book stores and try to get them to sell their comics. Comics from small companies generally start out in a few venues and expand as the popularity of the titles increases. Large comic companies also purchase the rights to popular smaller comics.