Toxic

Cathy Dennis, Henrik Jonback, Christian Karlsson and Pontus Winnberg wrote "Toxic" for Britney Spears, with the production duo Bloodshy & Avant handling production. The song was originally written with Janet Jackson in mind, but was first offered to Kylie Minogue, who turned it down after hearing a snippet in the record-company offices. Minogue later said she held no grudge about its success for Spears, comparing it to "the fish that got away." Recording took place at Murlyn Studios in Stockholm and Record Plant in Los Angeles, with mixing by Niklas Flyckt at Khabang Studios in Stockholm.

Released in 2003 as the second single from In the Zone, the track is a dance-pop song with elements of South Asian music. Its hook samples "Tere Mere Beech Mein" by Laxmikant–Pyarelal from the 1981 Bollywood film Ek Duuje Ke Liye, though the sample was cut up and later replaced in part by a re-recorded string arrangement. The lyrics draw an extended metaphor of a lover as a dangerous and addictive drug.

The song reached number one in countries including the United Kingdom, Australia, Canada and Ireland, and won Best Dance Recording at the 47th Annual Grammy Awards, the only Grammy win of Spears' career. Joseph Khan directed the music video, in which Spears played a secret agent who poisons her boyfriend. After the Super Bowl XXXVIII halftime show controversy, MTV deemed it too racy and moved it to late-night programming.