A duet by Carlos Santana and Rob Thomas, the latter of the rock group Matchbox Twenty. The song was written by Rob Thomas and Itaal Shur and sung by Rob Thomas. Originally conceived by Shur as a song called "Room 17," the lyrics were stripped off and the track was given to Thomas. Thomas re-wrote the lyrics and melody and re-titled it. Thomas's original thought was to have George Michael sing the song. Thomas recorded the song as a demo to play for Santana. After hearing the song being sung by Thomas, Santana decided to have Thomas record the final version. Matt Serletic produced the record and it was released from Carlos Santana's album Supernatural and became a massive hit in 1999, spending twelve weeks at number one on the Billboard Hot 100 at the end of that year. It was the first chart-topping song in Santana's long-running career (his previous biggest hit being "Black Magic Woman", number four in 1971). According to some charting standards, Smooth is Billboard's most popular song of all time. Though some songs have spent longer than 12 weeks at #1, when combining total sales during the entire time the song has charted, Smooth ranks higher than any other.

The song won three Grammy Awards, including Record of the Year, Song of the Year, and Best Pop Collaboration with Vocals. It spent a record-breaking ten consecutive weeks at the top of the VSpot Top 20 Countdown, a record that held up until the Dixie Chicks broke it in 2006. According to Billboard's Hottest Hot 100 Hits by Fred Bronson, this is the #1 song of The Nineties (2003).