DRM

From http://www.DigitalFreedom.org

Never before in history have copyright terms been so expansive. The big studios have gotten the limits on copyrights extended more than a dozen times, far beyond what the authors of the Constitution could have ever envisioned.

DRM (Digital Rights Management) is a technology used to control access to and usage of digital data or hardware, and is often used to prevent people from copying their music to share with others.  But, at times, it also prevents you from accessing music that you purchased (like if you wanted to switch from a Zune to an iPod, for example).
    There have been arguments throughout history for restricting access to music:

From DigitalFreedom.org...

" I foresee a marked deterioration in American music…and a host of other injuries to music in its artistic manifestations, by virtue—or rather by vice—of the multiplication of the various music-reproducing machines…"
- John Philips Sousa on the Player Piano (1906)

"The public will not buy songs that it can hear almost at will by a brief manipulation of the radio dials."
- Record Label Executive on FM Radio  (1925)

"But now we are faced with a new and very troubling assault on our fiscal security, on our very economic life and we are facing it from a thing called the videocassette recorder…"
- MPAA on the VCR (1982)

"These devices are just repositories for stolen music, and they all know it.  So it's time to get paid for it."
- Universal Music Group Chairman/CEO Doug Morris, November 10, 2006

Now corporations are trying to manipulate copyright laws to protect their bottom line, while restricting our access and taking away our freedoms.But check out this...

and this...