For questions about Unearthed Arcana, Wizards of the Coast's column featuring draft-form, unfinalized new content published for playtesting for D&D 5e.
For questions about Unearthed Arcana, a column published by Wizards of the Coast on the D&D 5e website featuring content from D&D R&D. This content consists of ideas the D&D 5e designers are experimenting with and have released to the public for play-testing and feedback, which may one day end up in official rules sources.
(Unearthed Arcana was also the title of a series of D&D books for various past editions.)
