What are graphic novels?Can u suggest any work?

A graphic novel is a type of comic book, usually with a lengthy and complex storyline similar to those of novels, and often aimed at mature audiences. The term also encompasses comic short story anthologies, and in some cases bound collections of previously published comic-book series.

Graphic novels are typically bound in longer and more durable formats than familiar comic magazines, using the same materials and methods as printed books, and are generally sold in bookstores and specialty comic book shops rather than at newsstands.

There is a huge collection of works on in. To know all that you can visit this url
http://en.wikipedia.org/wiki/Graphic_novel#Modern_form_and_term

Graphic Novels are a fast growing segment of the entertainment
industry. There are five television networks that are either dedicated
to or carry a major portion of graphic novel based cartoon series and
there are new movies, created from graphic novels, being released
monthly. Why not take advantage of this multi-billion dollar industry?
Kids LOVE graphic novels! If you’re looking for ways to bring the next
generation of readers into your library, Graphic Novels are the key

The evolving term graphic novel is not strictly defined, and is sometimes used, controversially, to imply subjective distinctions in artistic quality between graphic novels and other kinds of comics. It suggests a story that has a beginning, middle and end, as opposed to an ongoing series with continuing characters; one that is outside the genres commonly associated with comic books, and that deals with more mature themes. It is sometimes applied to works that fit this description even though they are serialized in traditional comic book format. The term is commonly used to disassociate works from the juvenile or humorous connotations of the terms comics and comic book, implying that the work is more serious, mature, or literary than traditional comics. Following this reasoning, the French term Bande Dessinée is occasionally applied, by art historians and others schooled in fine arts, to dissociate comic books in the fine-art tradition from those of popular entertainment, even though in the French language the term has no such connotation and applies equally to all kinds of comic strips and books.

source ,
wikipedia

The store generally will sell the graphic novel to you. I was buying 16+ graphic novels when I was thirteen, and my friend started buying them when she was twelve. It's up to your parents if you can read it, and my parents never cared because they trusted me to know if something wasn't worth buying. Some of my mangas they still might consider a bit questionable, but they never cared enough to look for a rating or to see what the mangas contain.