Dream Theater is an American progressive metal band formed in 1985 in Boston, Massachusetts, by guitarist John Petrucci, bassist John Myung, and drummer Mike Portnoy while they were students at the Berklee College of Music. Originally called Majesty, the band changed its name to Dream Theater in 1987. They released their debut album *When Dream and Day Unite* in 1989, but it was their second album, *Images and Words* (1992), that brought them mainstream success, featuring the hit single "Pull Me Under." This album established their signature sound, blending complex compositions, technical proficiency, and melodic elements. Throughout their career, Dream Theater has released numerous critically acclaimed albums, including *Metropolis Pt. 2: Scenes from a Memory* (1999), *Train of Thought* (2003), *Octavarium* (2005), and *A Dramatic Turn of Events* (2011). They have become known for their virtuosic musicianship and elaborate live performances. Mike Portnoy departed in 2010 and was replaced by drummer Mike Mangini. Despite lineup changes, Dream Theater has remained at the forefront of progressive metal, continuing to release albums and tour worldwide. Their influence on the genre is immense, and they are regarded as one of the greatest progressive metal bands of all time.