What is the Wikipedia sandbox and how is it used for drafting?

The Wikipedia sandbox is a drafting workspace, located at User:[username]/sandbox for any registered editor, where article content can be developed without being live in mainspace. The sandbox is where the drafting work actually happens for a new article: the article structure gets built, sources are added inline, the language is tightened to encyclopedic voice, and the content is reviewed before any external eyes see it. From the sandbox, the article can be moved to mainspace directly (faster but bypasses AfC review) or submitted to Articles for Creation for community review before publication. For COI work we work in the sandbox first, refine through internal review, and then submit through AfC with the COI disclosed. The sandbox does not protect against later challenges to the article but it does protect against the workflow problem of editing live and then trying to fix issues in public.