Formal language is characterized by the use of standard English, more complex sentence structures, infrequent use of personal pronouns, and lack of colloquial or slang terms. Informal language allows the use of nonstandard English forms, colloquial vocabulary and typically shorter sentence structures.
In "The Masque of the Red Death" by Edgar Allen Poe, Prince Prospero orders the gates of the abbey to be welded shut in order to protect himself and his inhabitants from the epidemic known as the "Red Death
