DRM of iTunes

I did some research on DRM (Digital Rights Management) in iTunes songs.  I managed to find the iTunes terms of agreement and found the part about DRM.

It made sense for a while, but now I'm all confused again....I read something about iTunes downloaded songs being allowed on 5 computers and 20 devices, then there was something else about unlimited amount of devices and 5 computers...damn iTunes make up your mind!


Then I asked my sister what she thought it was, and she said it was that you can only have your account on a certain number of computers...

So is DRM linked to accounts or songs? :[


Look here if you wanna try to figure it out.