Used in
photography to give an illusion of infinite space behind the subject. You need a really big one, and really good lighting, to take those tipical car pictures that end up in ads. There are mini-cycloramas (you can improvise on with cardoboard) for small object photography.
As all backgrounds in studio photography, they smudge and get soiled and are a general pain in the ass. Repainting the cyclorama in flat white is quite frequent.