Lets now hear Denny O’Neil, Batman editor and writer and if I may say, a living legend in the comics industry, says about this:

What are comics?

"They are not a collection of words and images printed on the same page. (That’s what illustrated books are.) To be a comic book, those words and images must work together as parts of speech work together as parts of speech work together in a normal English sentence. Think of comics as a language comprised of two separate and vastly different elements used in tandem to convey information. To be a good comics writer, you must be or become fluent in this hybrid language as you are in your mother tongue."