What constitutes Sequential Art?
To complement the description in the main tab, sequential art can be defined as the use of visual artworks with the purpose of telling a story. Some elements, like text, can be added, but they are not the central part. It can't be mostly text with a few illustrations thrown in either.
This leads us to the issue of graphic novels. They aren't sequential art pieces if taken as a whole product. However, one of the illustrated pages can very well be an example of this trope. A couple of vignettes adapting a scene from the text do apply. But that's the thing — it's just that series of vignettes on a page, not the novel itself.
Other than that, modern sequential artworks seem pretty clear cut — they are comics, be it Manga, Comic Strips, or Webcomics. The truth is that this trope has existed for quite a while throughout human history. The majority of them aren't even unbuilt tropes! Remember, the defining quality is that visual art —i.e., painting, sculpture, carvings, etc.— does the heavy lifting.
We could daresay that sequential art is one of the most ancient forms of art. Pictures on caves describing a tragic hunt? Hieroglyphics on Ancient Egypt tombs narrating how to traverse the dangerous Underworld? Ink-on-scroll drawings recounting an Edo period fable? Reliefs on a temple's walls immortalizing a myth of creation? All of them count as long as they have a plot, however simple it may be.
This latter detail is what differentiates, for example, The Ghent Altarpiece from the The Bayeux Tapestry. The former, yes, shows key moments from the Bible but not in a way that forms a cohesive story just from the scenes shown by the paintings. By contrast, the latter devotes each small embroidered vignette to narrating how the Normans conquered England. It's a sequence of events.
