AFI (A Fire Inside) is an American rock band from Ukiah, California, formed in 1991. They have had the same lineup since 1998: lead vocalist Davey Havok, drummer and backup vocalist Adam Carson, with bassist Hunter Burgan and guitarist Jade Puget, who both play keyboard and contribute backup vocals. Of the current lineup, Havok and Carson are the two remaining original members.

They have released nine studio albums, ten EPs, one live album and one DVD. The band first reached substantial commercial success with their fifth album, The Art of Drowning (2000), which peaked at number 174 on the Billboard 200.

AFI broke into the mainstream with their sixth album, Sing the Sorrow (2003), which peaked at number five on the Billboard 200 and remained on the chart for 51 weeks. The album was supported by popular singles "Girl's Not Grey" and "Silver and Cold", both of which peaked at number seven on America's Hot Modern Rock Tracks chart in 2003. "The Leaving Song Pt. II" was also released as a single, reaching number 16 on the chart. Sing the Sorrow was certified Platinum by the RIAA in 2006 and is AFI's best-selling release, having sold over 1.26 million copies as of September 2009.

Their seventh album, Decemberunderground (2006), debuted at number one on the Billboard 200 and featured the hit single "Miss Murder", which topped the Hot Modern Rock Tracks chart and reached number 24 on the Billboard Hot 100. Another single, "Love Like Winter", reached number four on the Modern Rock Tracks chart. Decemberunderground was certified Platinum by the RIAA in 2013.

AFI's eighth studio album, Crash Love, was released in 2009 and peaked at number 12 on the Billboard 200. Their ninth album, Burials, was released in 2013 and peaked at number nine on the Billboard 200. As of 2016, they are working on the follow-up to Burials.

AFI is known for playing several genres of rock music; the band originally was a hardcore punk/punk rock band, eventually moving to genres such as post-hardcore, and emo.