I've always divided 2D graphics of the kind you see in Apps (let's ignore 3D Graphics cards with shaders/textures/etc.. for a bit) into two categories - bitmap

I've always divided 2D graphics of the kind you see in Apps (let's ignore 3D Graphics cards with shaders/textures/etc.. for a bit) into two categories - bitmap and vector graphics. Bitmap is pretty straighforward, and vector graphics (googling for a second) is "...the use of geometrical primitives such as points, lines, curves, and shapes or polygons" - which presumably Marco is doing to keep his app size so small?