Ain't?

  •  
  • 48
  • 6
  • 1
  • English 
Jul 28th 2011 22:05 ain't dialect English word
I hear this word once in a while, for example in a song, a film or on radio.
It's a short term of "am not"/"is not"/"are not", right?
But I've never used it myself before. I'm not sure when you use it. Or you shouldn't.
Can you help me out?
Thank you!