non orientable shapes, what does that term mean and how it affects the shape being non orientable


Title says it all, mobius strips, Kline bottles etc. I understand they have no start and finish but what does orientable and non orientable mean and why do they exist


It means you can start at one point, walk on the shape, and get back to that same point finding yourself upside down. This wouldn’t be possible on a sphere (which is orientable).