"Sandboxes" are places for users to practice more advanced edtiting without damaging a page on the wiki. Like a real sandbox, users can play with codes, formats, etc. and destory it all afterwards without hurting a real article.
Each user can create thier own personal sanbox by creating a page such as [[
User:yournamehere/sandbox]] (without the brackets. The page is case sensitive).
See Help:Sandbox for more information.