5 Seconds of Summer, often shortened to 5SOS (pronounced as '5 sos'), are an Australian pop rock band from Sydney, New South Wales, formed in late 2011. The group consists of lead vocalist and rhythm guitarist Luke Hemmings, lead guitarist Michael Clifford, bassist Calum Hood, and drummer Ashton Irwin. Originally beginning their career as YouTube celebrities, they rose to international fame while touring with English-Irish boy band One Direction on their Take Me Home Tour. Since 2014, 5 Seconds of Summer have sold more than 10 million albums, sold over 2 million concert tickets worldwide, and the band's songs streams surpass 7 billion, making them one of the most successful Australian musical exports in history.

In early 2014, the band released "She Looks So Perfect" which topped the charts in four countries. Their self-titled debut album was released in 2014, peaking at number one in 11 countries. The band released their second album Sounds Good Feels Good in 2015, topping the charts in 8 countries. The band's third album Youngblood, released in 2018, was a commercial success and became their third number one album in their home country. In the US, 5 Seconds of Summer became the first Australian act to achieve three number one albums on the Billboard 200 album chart. They also became the first band (not vocal group) to have their first three full-length albums debut at the top in the US. The album's single, "Youngblood" is the fourth highest selling Australian single of the 2010-2019 decade and is the eleventh best-selling single in Australian history.