Digital Rights Management (popularly known simply as DRM) has many different meanings. Broadly speaking, it is considered as a way to protect the intellectual property after sale.
The question of the need of DRM is controversial and attracts a wide range of opinions. Some people assert that it is a necessary a tool in this technological age to combat piracy. Others, argue that DRM does very little against piracy, and acts more as an unnecessary hindrance for the consumers.
Regardless of where your opinion lies on the, it appears that there is a shift in the music industry away from the use of DRM. Back in 2007, Amazon launched their mp3 service where consumers can purchase mp3s without DRMs. Shortly after this, Apple’s iTunes store introduced the option to buy songs DRM free, and to remove the DRM from songs already purchased (for an additional price). More recently with the launch of Google’s Play Store, its hard to see DRM in music as anything but a thing of the past.
Without DRM, it remains to be seen how (and if) the music industry will continue the protection of their intellectual property after the sale of their product.