For the last eight years, the Free Software Foundation has been campaigning to stop the widespread use of DRM, a technology with the supposed intention to stop us from making illegal copies of digital goods. Once a year, on May 6th, they hold the International Day against DRM, as a means of protesting this technology.
Officially, DRM stands from Digital Rights Management, because it's advertised purpose is to protect copyrights from infringers. However, DRM is often used to prevent people from doing certain activities that would otherwise be 100% legal, such as transcoding copyrighted videos to from one format to another, selling goods second-hand, and making backup copies. For this reason, the Free Software Foundation prefers the term Digital Restrictions Management, because it restricts your freedom.
Please note: DRM doesn't actually stop people from breaking copyright law, as many infringers will simply crack the protection, resulting in the production of unencrypted copies. In fact, the mere use of DRM is often why many users prefer illegal copies of works, as these copies can be backed up, transcoded, played/executed on devices they weren't meant to be played/executed on, etc.
However, DRM is dangerous in many other ways, even if you don't plan on making copies of anything. A few years ago, people who had purchased legal copies of the George Orwell novel Nineteen Eighty-Four from Amazon, found themselves the victims of massive theft; Amazon decided to use its DRM system to delete every copy of this book they had ever sold, without warning or refund. DRM is also used for anti-competition practices. This is becomming surprisingly common in the printer industry: DRM is used to ensure you can only use name-brand ink/toner for your particular printer. If the cartridge is refilled (instead of being replaced), your printer may refuse to use this cartridge altogether. Even electric cars now come with DRM, which is used to the disadvantage of the owner.
See HERE if you wish to get involved.