Singer Justin Bieber teams up with rapper Ludacris in the song "Baby."
Released in 2010, "Baby" was the lead single from Bieber's first full studio album, "My World 2.0." The track pairs Bieber's youthful pop vocal with a rap verse from Ludacris, whose appearance helped give the song a broader hip-hop and contemporary-R&B profile.
The song was written by Bieber with producers Christopher "Tricky" Stewart and The-Dream, along with Ludacris and Christina Milian. Ludacris is therefore both the featured rapper heard on the recording and one of its credited co-writers. The collaboration became one of Bieber's signature early-career hits.
People sometimes confuse Ludacris with Usher, who was Bieber's mentor and played an important role in introducing him to the music industry. Usher is not the rapper featured on "Baby." Ludacris is the correct answer because his verse appears directly in the song and in its widely seen music video.