Opeth are a Swedish progressive metal band from Stockholm, formed in 1990. In addition to progressive metal, the band incorporates folk, blues, classical, and jazz elements into its usually lengthy compositions, as well as strong influences from death metal, especially in their early works. Songs may include acoustic guitar passages, Mellotrons, death growls, and strong dynamic shifts. The band rarely made live appearances supporting their first four albums, but since their first world tour in support of the 2001 album Blackwater Park, they have had several other major world tours. The group have been through several personnel changes since early in their history, including the replacement of every original member. Lead vocalist, guitarist and primary songwriter Mikael Åkerfeldt has been Opeth's driving force since the departure of founder and lead vocalist David Isberg in 1992.