A two-dimensional shape is a shape that has width and length but no depth. Another term for a two-dimensional shape is a plane shape, because a two-dimensional shape occurs on one plane, a flat surface that extends in every direction.
Two-dimensional shapes take up area but not volume. Geometric two-dimensional shapes have straight or curved edges that require tools, such as a straight edge or compass, to draw properly. These include triangles, squares, rectangles and circles. Organic two-dimensional shapes are formed of irregular lines. The qualities of geometric two-dimensional shapes are studied in the discipline of plane geometry. Although objects are sometimes portrayed by two-dimensional shapes, all real-world objects have some depth and take up volume, making them three-dimensional.