what the hell is ICM?

I haven't played a lot lately, but in some reading I've done, I've come across a concept called ICM (The Independent Chip Model). It seems I'm late to the party on this. From the beginning of what I've read, it's about making decisions based on math and position relative to the money. I read through someone named Jennifear's $55 STT which had some interesting plays and thoughts:

http://www.pocketfives.com/0DBF774F-1FC9-4349-825D-9BE7645FCF20.aspx

I want to do some reading on ICM and see if it can help me short handed STT bubble game.

I also want to focus more when playing - my play was not tight today, too many loose plays. I'm better than this.