Napster was the name given to two music-focused online services. It was originally founded as a pioneering peer-to-peer (P2P) file sharing Internet service that emphasized sharing audio files, typically music, encoded in MP3 format. The original company ran into legal difficulties over copyright infringement, ceased operations and was eventually acquired by Roxio. In its second incarnation Napster became an online music store until it was acquired by Rhapsody from Best Buy on December 1, 2011.