In mathematics, specifically in topology, a surface's a two-dimensional topological manifold. The most familiar examples are those that arise as the boundaries of solid objects in ordinary three-dimensional Euclidean space R3. On the other hand, there're surfaces which can't be embedded in three-dimensional Euclidean space without introducing singularities or intersecting itself — these are the unorientable surfaces. To say that a surface's "two-dimensional" means that, about each point,… (More on Surface)