Testament formed in 1983 in the San Francisco Bay Area as Legacy, founded by guitarists Eric Peterson and Derrick Ramirez in Berkeley, California. The initial lineup included bassist Greg Christian, drummer Louie Clemente, and vocalist Steve 'Zetro' Souza, who later joined Exodus. In 1986, the band renamed to Testament due to a naming conflict and replaced Souza with Chuck Billy, releasing their debut album The Legacy in 1987, followed by The New Order (1988) and Practice What You Preach (1989). The band developed a thrash metal style marked by technical guitar work from Alex Skolnick, who joined early, and aggressive songwriting addressing themes of society, suffering, and death. Lineup changes occurred in the 1990s, with Skolnick and Clemente departing, but reunions produced albums like The Formation of Damnation (2008). Testament maintains an active presence with core members Peterson and Billy. Testament performances emphasize precise, high-energy thrash delivery, sustaining their reputation in live settings through enduring Bay Area thrash traditions.