A short sale is a sale of a house for less than what is owed on the mortgage, which requires the lender's written approval since the lender is agreeing to accept less than the full payoff. It usually takes longer to close than a normal sale because of that approval process, and it can still leave the seller owing a deficiency unless the lender agrees to waive it.
Why it matters
A short sale needs your lender's sign-off, so the timeline is largely out of your hands.
General information, not legal or tax advice.