Set of points that form a two-dimensional space.

- The measure of a surface is called the area.
- The area of a square is the measure of the surface of the square.

### See also :

### Educational note

The space that can be enclosed by a 2-D shape is not always 2-dimensional, since a 2-D space can be used to enclose a 3-D space (for example, the net of a cylinder is 2-D, but it can enclose a 3-D cylindrical space).