"Baby" is a song by Canadian recording artist Justin Bieber. It was released as the lead single from the latter half of Bieber's debut album, My World 2.0. The track was written by Bieber with Christopher "Tricky" Stewart and Terius "The-Dream" Nash, both of whom worked with Bieber on "One Time", and also by R&B singer Christina Milian and labelmate, rapper Ludacris.