A ruled surface is a geometric concept defined in 3-dimensional Euclidean space. A surface is considered ruled if, for every point on the surface, there exists at least one straight line that lies entirely within that surface. This property allows complex shapes to be described or constructed using linear components.
Common examples of ruled surfaces include the plane, the lateral surfaces of cylinders and cones, and various specialized forms such as the helicoid and the right conoid. Additionally, the tangent developable of a smooth curve in space is also classified as a ruled surface, demonstrating the versatility of this geometric definition across different mathematical contexts.