what is manifold and non-manifold surface

as the subject.

can someone explain these two concepts in plain english? i have check out the wikipedia but i got lost in half way of reading it.
so maybe guru other there can explain these two concepts with simple and clear statements.


This should clarify things :

shortest description i’ve heard that i thought helped was that a manifold surface is one in which every edge is adjacent to two faces. i believe that property is necessary and sufficient.

e.g. a triangle is not a manifold surface - each edge is adjacent to a single face. a cube is a manifold surface. if you take one face away from the cube, it is no longer manifold.

some properties that come out of this - no open boundaries (like the cube missing a face), the surface is “air-tight”, it has a distinct inside and outside surface, etc.

non-manifold is any surface that doesn’t meet the requirement for a manifold surface.

Basically, a manifold surface is a surface that completely encloses a volume.