Invented in the early 90's, reshaping the whole industry - The MPEG-1 Layer III, a.k.a. "MP3". According to a recent study, the dominating lossy compressed audio format is finally experiencing a slight decline in popularity. The source only mentions Microsoft's WMA (..I wonder why..) as one of the rising formats, but it is reasonable to believe that AAC (Advaneced Audio Compression) will be the successor of MP3. The AAC has been promoted by Apple and Ahead Software (Nero Burning ROM) and is widely adopted by the mobile phone industry already.
MP3 is still the overwhelming favourite of file traders, but the once-universal format's popularity has been going quietly but steadily down in personal music collections for the last year. According to researchers at The NPD Group's MusicWatch Digital who track the contents of people's hard drives, the percentage of MP3-formatted songs in digital-music collections has slid steadily in recent months, down to about 72 percent of people's collections from about 82 percent a year ago.Source: ZDNet