"Copy protection, also known as content protection, copy obstruction, copy prevention and copy restriction, is any effort designed to prevent the reproduction of software, films, music, and other media, usually for copyright reasons. Various methods have been devised to prevent reproduction so that companies will gain benefit from each users who obtain a copy of their product. Unauthorized copying and distribution accounted for $2.4 billion in United States in 1990s, and is assumed to be causing impact on revenues in music or game industry, leading to proposal of anti-piracy laws such as PIPA. Some methods of copy protection have also led to criticisms because it caused inconvenience for honest users or secretly installed additional software to watch activity on user's computer to detect copying. Effective copy protection as well as protecting user rights is still an ongoing problem with media publication."