NSYNC ( en-SINK, in-; also stylized as *NSYNC or 'N Sync) is an American vocal group and boy band formed by Chris Kirkpatrick in Orlando, Florida, in 1995 and launched in Germany by BMG Ariola Munich. The group consists of Kirkpatrick, Justin Timberlake, Joey Fatone, Lance Bass, and JC Chasez. Their self-titled debut album was successfully released to European countries in 1997, and later debuted in the U.S. market with the single "I Want You Back".

After heavily publicized legal battles with their former manager Lou Pearlman and former record label Bertelsmann Music Group, the group's second album, No Strings Attached (2000), sold over one million copies in one day and 2.4 million copies in one week, which was a record for over fifteen years. NSYNC's first two studio albums were both certified Diamond by the Recording Industry Association of America (RIAA). Celebrity (2001) debuted with 1.8 million copies in its first week in the US. Singles such as "Girlfriend", "Pop", "Bye Bye Bye", "Gone", and "It's Gonna Be Me" reached the top 10 in several international charts, with the last being a US Billboard Hot 100 number one.

In addition to eight Grammy Award nominations, NSYNC performed at the Super Bowl and sang the national anthem at the Olympic Games and World Series. They have also sung or recorded with Elton John, Stevie Wonder, Michael and Janet Jackson, Britney Spears, Phil Collins, Celine Dion, Aerosmith, Nelly, Lisa "Left Eye" Lopes, Mary J. Blige, country music band Alabama, and Gloria Estefan. NSYNC went on a hiatus in 2002 and reunited in 2023 to release the single "Better Place" for the DreamWorks animated film Trolls Band Together (2023).

Over the course of their hiatus, the five members reunited occasionally, including at the 2013 MTV Video Music Awards and to receive a star on the Hollywood Walk of Fame in 2018. The band completed five nationwide concert tours and has sold over 70 million records, becoming one of the best-selling boy bands of all time. Rolling Stone recognized their instant success as one of the Top 25 Teen Idol Breakout Moments of all time.