* What's: This is a contraction of "what is" or "what has".
* Example: "What's your name?"
* What've: This is a contraction of "what have" (less common, but still acceptable).
* Example: "What've you been up to?"
Keep in mind that contractions are more common in casual speech and writing. In formal writing, it's usually best to use the full form of "what is" or "what have."