It’s hard for computer to draw most shapes since they have complicated non-linear formulas
Collection of points connected with lines. Can be represent by connecting several vertices
There are different types of polygons as well. Like closed/open, wireframe/filled, planar/non-planar, convex/concave etc.
The data structures used to represent the polygonal model is the indexed face set. It maps the index of faces to vertex list and maps the index of the vertices to their coordinate.