"Circus" is a song by American pop singer Britney Spears from her sixth studio album of the same name. It was released on December 2, 2008, by Jive Records as the second single from the album. The song, produced and co-written by Dr. Luke and Benny Blanco, talks about Spears abilities as an entertainer and compares them to performing in a circus. Musically, "Circus" is an uptempo dance song, with influences of R&B. Backing vocals are provided by Cathy Dennis.
"Circus" has received positive reviews from music critics, many praising the song’s production. The song has achieved commercial success as well, topping the charts in Turkey, reaching the top five in the United States, Canada and New Zealand and the top ten in many other countries. The music video features Spears as the ringleader of a circus and was directed by Francis Lawrence. The song has been performed on Good Morning America as well as in The Circus Starring: Britney Spears, where she performs it as the opening song of the show wearing a ringleader outfit and carrying a whip.