Wit is a form of intellectual humour. A wit is someone skilled in making witty remarks. A witty remark is a smart observation, put with humor and said in the perfect moment. Forms of wit include: the quip and the repartee.
Witty remarks may be intentionally cruel, and may be more ingenious than funny.
A quip is an observation or saying that has some wit but perhaps descends into sarcasm, or otherwise is short of point; a witticism also suggests the diminutive. Repartee is the wit of the quick answer. (Wilde: "I wish I'd said that." Whistler: "You will, Oscar, you will".)