There are two separate parts to every song released:
1. The sound recording / master recording: Dependent upon contract, the master can be owned and controlled by the performing artist(s) on a track, the record label and/or any producer(s) involved in the creation of the recording.
2. The musical composition (a.k.a. song, underlying composition, musical work, etc.): Dependent upon contract, the musical composition is owned and controlled by the songwriter/composer(s), and the publisher if applicable. If there is no designated publisher involved, the songwriter is automatically the owner in control of his/her composition.
Each one of these art forms represents a separate ownership and a separate part of the music business.
Let’s say Taylor Swift and her favorite co-songwriter write a song together on her guitar in the studio and write the notes down on a sheet of staff paper. She then records it with the help of her band and record label. Since she’s such a famous pop artist, her publisher will transcribe her and her co-songwriter’s song into a sheet music book that everyday musicians worldwide can read and play at home. The sheet music represents her and her co-songwriter’s musical composition; the song you buy on iTunes is the master recording/sound recording. They are two distinctly different things, and each drives two entirely separate aspects of the music industry. Music publishing is the business of exploiting her musical composition and collecting the maximum amount of ensuing royalties. The recording industry (record labels) is the business of marketing and selling sound recordings of songs. Taylor Swift is both a songwriter AND a performing artist.
Let’s say Deadmau5 sits down in his studio one morning and, 24 hours later, he’s staring at his next big dance single on the computer screen. He decides to release the recording on his own label Mau5trap. Even though Deadmau5 is a producer and didn’t exactly write the melodies and harmonies down on a piece of staff paper like Ms. Swift did, his recording contain a musical composition embedded within; it still has a “publishing side” and a “master side.” It’s just that the musical composition is more virtual this time, instead of tangible. But the musical composition is still in tact. Deadmau5 is both the composer and performing artist on this new single.
In today’s world, the vocabulary between the sound recording world and the publishing world can be confusing since so many independent musicians releasing music now are both the songwriter and the performer. For ultimate clarity, whenever discussing the “publishing” world or anything related to the musical composition, we use the terms “songwriter,” “writer,” or “composer” (Rather than “artist”).