What are some of the key literary elements in The Crucible by Arthur Miller, and could you please give examples?

One of the most significant literary elements employed by this play is irony.  Certainly, Act III presents us with major situational irony -- when something about a situation itself defies expectation -- when Deputy Governor Danforth refuses to believe the truth told by Mary Warren and John Proctor and, instead, believes Abigail Williams and the other girls who are actually lying.  He tells Proctor, "We burn a hot fire here; it melts down all concealment," when, in fact, this judge is completely incapable of detecting concealment and deception.  It is ironic that a judge is incapable of winnowing out truth from lies.

Miller also employs dramatic irony -- when the audience knows more than a character -- in this act.  We know that Mary and Proctor are telling the truth; we know that there is no such thing as witchcraft, for that matter.  However, Danforth cannot see that his belief that "the voice of Heaven is speaking through the children" is incorrect.  He is mistaken, and he condemns many innocents as a result of his error.  We know more than he does, and this builds tension and suspense for the audience as we await the revelation of truth.