Artists contracts looks differently depending upon which country they are from, what genre of music they produce and where they are in their career stage.
Example: Electronic artists tend to sign track deals and these deals can be done individually to different labels. In this particular situation the record label signs the song but not the artist.
The music industry is become even more singles driven and this benefits labels as they don’t need to take as much risk signing an artist when they can just sign a single deal. Additionally, it allows the artists to pick and choose the best labels depending upon their release.