Metadata is data about data. Metadata is contained in virtually every device that collects data today.
The Motion Picture Association of America has created techniques and tracks to identify each individual film that is distributed. The movie you see at the theater most likely has scratches or a light code imbedded in it. Pirates who bring cameras in the theater routinely get convicted when the prosecution discovers the embedded data from the original.
SOPA would allow the U.S. government to shut down websites and prevent access to sites considered offensive. At the other end of the spectrum, the government of Sweden has a recognized a group that promotes file-sharing as a religion.
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