Article 1, Section 8 of the Constitution of the United States:
"Congress shall have the power to ... To promote the Progress of Science and useful Arts, by securing for limited times to Authors
and Inventors the exclusive Right to their respective Writings and Discoveries."
U.S. COPYRIGHT ACT
Grants Exclusive Rights to Copyright Authors or Owners
Right to Reproduce
Right to Make Derivative Works
Right to Distribute
Right to Perform
Right to Display
EVERY RECORDED SONG CONTAINS TWO COPYRIGHTS
1) MUSICAL COMPOSITION
The notes and lyrics of the song
2) SOUND RECORDING
The Recording Artist's recorded version of the song
Even if the recording artist is the songwriter, two copyrights are created - one for the sound recording and one for the musical composition.
What is a Music Publisher
A music publisher works with songwriters to market and promote their songs, resulting in exposure of songs to the public and generating income. Music publishers "pitch" songs to record labels, movie and television producers and others who use music, then license the right to use the song and collect fees for the usage. Those fees are then split with the songwriter.
Music Publishers and Record Labels
Songwriters enter into publishing, co-publishing, or administration agreements with music publishers. In exchange for acquiring the copyright, a portion of the copyright, or a percentage of the revenue earned from the exploitation of the musical composition, the music publisher seeks opportunities to exploit the musical composition, collects revenue from the exploitation, and pays and accounts to the songwriter. The music publisher share is usually 50%.
Recording artists assign their copyrights to a record label in exchange for a negotiated royalty.
The above excerpt is provided courtesy of the National Music Publishers Association / "Music Publishing 101" - Copyright 2014