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Songs and software, despite being shared in small percentages of swarms (4.5% and 7.2% of swarms respectively), rank 2nd and 3rd in terms of transfers (with 20.4% and 16.8% of transfers respectively). Movies are the type of content most supplied and most transferred in BitTorrent (shared in 38.7% of swarms and accounting for 26.1% of transfers). Thus, we conclude that BitTorrent transfers result in hundreds of millions of copyright violations worldwide per day, and that copyright holders fail to realize significant revenues as a result. We also find that the vast majority of music and video content transferred using BitTorrent is copyrighted, as demonstrated both by the swarm metadata we observed, and the fact that only 0.55% of the transfers were of files indexed by websites that specialize in content that can be transferred legally.
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For example, we estimate that 10.7 songs were transferred using BitTorrent for every song sold, 3.6 movies were transferred using BitTorrent for every legal sale or rental of a DVD or Blu-ray, and 227 movies were transferred using BitTorrent for every paid download. Using data we collected from the largest public BitTorrent tracker over 106 days between August 2010 and February 2011 and a new methodology, we find that for some content types, the number of copies transferred is an order of magnitude greater than the number sold through legal channels.
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This paper presents the most accurate empirical study to date to characterize and quantify the amount of content of various types that is transferred worldwide using BitTorrent, the dominant peer-to-peer (P2P) file sharing application.
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