The CSS (Content Scrambling System) is the encryption method used in commercial DVD production to prevent DVD data from being copied. The sole purpose of the CSS is to protect copyrights by preventing the pirating of DVDs.
The CSS decryption, called DeCSS (De-Content Scrambling System) is an algorithm that can be used to decrypt a commercially-produced DVD, allowing it to be unlocked then copied. In January, 2000, the development of DeCSS was blamed on Jon Johansen, a fifteen year old boy from Norway. Charges against Jon Johansen were dismissed in January, 2003.
DeCSS is used by several DVD copy software manufacturers to decrypt DVDs; some include it with the software, others require you to download the algorithm from the internet before the software will work. At TopTenREVIEWS We Do the Research So You Don't Have To.™