Apparent nothingness. In this case, seamless white. Usually shot on a stage with a cove, so the floor slopes up to meet the wall in a seamless continuous sweep. When properly lit, floor and walls are all the same white nothingness. In the Apple case, it is possible that behind her is just a white wall since the shot is cut at her waist. In general, you want the wall far back from the subject so, as with green screen, you light the subject with one set of lights, and the wall/floor with another.
If you need to to see the floor too, then space lights, preferably through silk, are a common solution. If you don't know what space lights are, do a google search. Equally, you could have done a google search for "lighting limbo". Lots and lots of information there.
Rick Wise
director of photography
Oakland, CA
http://www.RickWiseDP.com
email: Rick@RickWiseDP.com
