Answer by taking a quote from the following article:

Geoff Tate (born Jeffrey Wayne Tate, January 14, 1959; he later changed his first name to Geoffery or Geoffrey) is a German-born American singer and musician. He rose to fame with the progressive metal band Queensryche, who had commercial success with their 1988 album Operation: Mindcrime and 1990 album Empire. Tate is ranked fourteenth on Hit Parader's list of the 100 Greatest Metal Vocalists of All Time.

While Tate was in the band Babylon, he was asked to sing with the cover band The Mob (who would later start writing original material and become Queensryche) at a local rock festival. After Babylon broke up, Tate performed a few shows with The Mob, but left because he was not interested in performing heavy metal cover songs. Tate then joined the progressive metal band Myth as lead vocalist and keyboardist. Other band members of Myth included Kelly Gray, who was later one of the replacements for Queensryche guitarist Chris DeGarmo, and Randy Gane, both of whom joined Tate's version of Queensryche in 2012.  The Mob again called on Tate in 1981, this time to record a demo tape, which he accepted, convincing his bandmates in Myth that getting professional recording experience would benefit all of them in the future. The band already had a set of songs, but one song was still left without lyrics. Tate was asked to write lyrics to this song, which would become the song "The Lady Wore Black", Tate's first penned song with the band. The demo tape was widely circulated, and was released as an EP in 1982 on the 206 Records label. Around this time, the name The Mob was changed to Queensryche, and Tate left Myth to become Queensryche's permanent lead singer. Myth went on to record the album Arabia after Tate had left.  Queensryche was signed to EMI in the summer of 1983, with a contract spanning 15 years and encompassing seven albums. EMI re-released the EP, Queensryche, to moderate success, peaking at No. 81 on the Billboard charts. With Queensryche, Tate had great successes, especially with the concept album Operation: Mindcrime, which was released in 1988, and 1990's Empire. The band has sold over 20 million albums worldwide.  On June 20, 2012, it was announced that Queensryche had fired Tate, replacing him with Crimson Glory vocalist Todd La Torre. Soon after, Tate and his wife Susan (who served as the band's manager from 2005-2012) filed a lawsuit in a Washington court, saying that he was wrongfully terminated from the group. They also filed a preliminary injunction in an attempt to prevent either side from using the band's name and likeness until the lawsuit was settled, but this was denied by a judge who decided that both parties can use the name Queensryche until a settlement or a court verdict determines who gets the name. It was revealed to the public on April 28, 2014 that Rockenfield, Wilton and Jackson were given the exclusive rights to the Queensryche trademark and that Tate received the rights to Operation: Mindcrime.

what is queensryche
The Mob (who would later start writing original material and become Queensryche