A shape is an object that has some form of distinguishable external boundary, surface, or outline.
The line segments or curves forming a closed shape are continuous, meaning there is no break. The lines/curves must also form a closed region to be considered a closed shape:
The segments or curves of an open shape are not always connected. At least one endpoint of one side is not connected to the rest:
A polygon is a closed plane figure formed by line segments. The following is a list of some polygons.
This is not an exhaustive list of polygons. If there are n sides for a polygon, we call it an n-gon.
The following is a list of some non-polygon shapes.
|Shapes with a curve
|Open 2D shapes
A polyhedron is a closed solid whose faces are polygons. The following is one way to further classify polyhedra.
There are many more prisms and pyramids, but only five platonic solids (regular, convex polyhedrons), the tetrahedron, cube, octahedron, dodecahedron, and icosahedron.
A non-polyhedron is a solid that has surfaces that are fully curved or partially curved.
|Partially curved surfaces
|Fully curved surfaces
Each shape above can be further classified. For example, a quadrilateral can be further classified as a parallelogram, rectangle, trapezoid, square, and more. Learn more about specific shapes and their classifications by navigating this website.