5 seconds of summer are a band from Australia. Consisting of Luke Hemmings, Michael Clifford, Calum Hood and Ashton Irwin, four teenage boys who gained their fame though posting videos of themselves preforming popular songs together on YouTube. They began to gain a small following in 2012 and rose to international fame after One Direction invited them onto one of their tours. Later releasing their debut single 'out of my limit' in November 2012. Although 5 seconds of summer have been closely linked with One Direction they are adamant not to be described as a boy band. Any true 5SOS fan needs to array their walls with 5SOS posters!