The CSS (Content Scrambling System) means that DVD manufacturers have converted the data into a code so that it cannot be easily duplicated. You probably realize that the film and DVD industry does not want consumers to copy DVDs, so the purpose of CSS is to sabotage efforts to copy DVDs. CSS decryption then is a mechanism to undo the scrambling effect of CSS so that a DVD can be copied. Interestingly CSS was developed by a fifteen year old boy from Norway. Though legal action was attempted against the boy, the case was dismissed in 2003. Since then DVD copy software has been utilizing CSS. Some companies include CSS within the software while others leave out CSS which requires the user to download the component from the Internet.