Developable surface

That is, it is a surface that can be flattened onto a plane without distortion (i.e. it can be bent without stretching or compression).

Conversely, it is a surface which can be made by transforming a plane (i.e. "folding", "bending", "rolling", "cutting" and/or "gluing").

[1] The envelope of a single parameter family of planes is called a developable surface.

Since developable surfaces may be constructed by bending a flat sheet, they are also important in manufacturing objects from sheet metal, cardboard, and plywood.

Some of the most often-used non-developable surfaces are: Many gridshells and tensile structures and similar constructions gain strength by using (any) doubly curved form.