<Tr> <Th_colspan="2"> Music video </Th> </Tr> <Tr> <Td_colspan="2"> "Baby" on YouTube </Td> </Tr> <P> "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 . </P> <P> It was available for digital download on January 18, 2010 . The song received airplay directly after release, officially impacting mainstream and rhythmic radio on January 26, 2010 . The song is uptempo R&B, blending together dance - pop and hip - hop elements, while using influences of doo - wop music . The song has received positive reviews from critics who complimented the song's effective lyrics and chorus, and commended Ludacris' part and the song's ability to have an urban twist . </P>

Who wrote the song baby by justin bieber