AC/DC are an Australian hard rock band, formed in November 1973 by brothers Malcolm and Angus Young, who continued as members until Malcolm's illness and departure in 2014. Commonly referred to as a hard rock or blues rock band, they are also considered pioneers of heavy metal and are sometimes classified as such, though they have always dubbed their music as simply "rock and roll". To date they are one of the best-selling bands of all time, with a total of more than 200 million albums sold worldwide. AC/DC underwent several line-up changes before releasing their first album, High Voltage, on 17 February 1975; Malcolm and Angus were the only original members left in the band. Membership subsequently stabilised until bassist Mark Evans was replaced by Cliff Williams in 1977 for the album Powerage. Within months of recording the album Highway to Hell, lead singer and co-songwriter Bon Scott died on 19 February 1980 after a night of heavy alcohol consumption. The group considered disbanding, but buoyed by support from Scott's parents, decided to continue and set about finding a new vocalist. Ex-Geordie singer Brian Johnson was auditioned and selected to replace Scott. Later that year, the band released the new album, Back in Black, which was made as a tribute to Bon Scott. The album launched them to new heights of success and became their all time best-seller, selling over 10,000 copies a day in its first week.