sand box is a kind of google's supplimental index, where google keep those websites which it thought suspicious. By saying suspicious I mean that google do not trust the website's authenticity in terms of the visitors' experience. Also the sand box applies to only new websites. If you are promoting a new website, doing lots of stuff to get back links it may sand boxed. The effect that became called the "sandbox" was happening in 2005 and the effect went away well over a year ago.
Yes Sandbox exists for more information about sandbox you can refer to wikipedia and type sandbox effect it will give you the detailed information about what sandbox is ???....