5 Seconds of Summer, often shortened to 5SOS, are an Australian pop rock band formed in Sydney in 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 have attained more than 7 billion streams of their songs on music streaming services, making them one of the most successful Australian musical acts in history.