"The rub comes from the music Apple sells on its online iTunes Store. Since Apple does not own or control any music itself, it must license the rights to distribute music from others, primarily the “big four” music companies: Universal, Sony BMG, Warner and EMI. These four companies control the distribution of over 70% of the world’s music. When Apple approached these companies to license their music to distribute legally over the Internet, they were extremely cautious and required Apple to protect their music from being illegally copied. The solution was to create a DRM system, which envelopes each song purchased from the iTunes store in special and secret software so that it cannot be played on unauthorized devices."
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