Inverse funds

Another forum mentioned reverse funds pegged to the S&P, Dow, etc.   Is this a short term hedge?  What happens if you bet wrong?  Somebody have the 101?

 

 

Then you lose.  The inverse is what it means.  If the index is up 5% then the fund will be down 5%.  Don't stay too long, because the inverse funds suffer an unusual amount of slippage.