There are different ways to draw a triangle in opengl. The straightforward way is to draw the triangle by passig in its’s three vertices. But because triangles almost always share their vertices with other triangles a more suitble way would be to take use of this knowledge. In OpenGL you can do it by either drawing triangles as strips (image below) or fans. The mostly used method is strips. If allowing triangles to have zero area then any coherent model can be interpreted as a long triangle strip. New graphics cards are built to be able to handle such triangles with zero area very fast. The profit from using triangle strips will be a lower memory usage and less accesses to memory.