Graphic Novel is a term used to describe a book that made mostly of images but tells a story. (This should not be confused with a novel that is graphic which is a totally different thing.)
For eBook use a graphic novel is often generated in three main formats, PDF, CBR and CBZ. It could also be shown in SWF or AAX formats. For iOS or Android it may be its own app. The target audience is often older children or teenagers. See also eBook reading for children. Do to the popularity of ePub the graphic novel is sometimes provided in this format as well. In particular there is a new fixed layout ePub that is designed for this purpose. If the Novel is a collection of CBR or CBZ files the format CBC can collect them into one file.