Accept formed in Solingen, Germany and slowly built a following in Europe during the late 1970's and early 1980's. [For hard rock fans, I would recommend "Fast As a Shark" from the 1982 Restless and Wild LP and "Balls to the Wall" from the 1983 album of the same name.]
Following the modest success of Balls to the Wall, which hit #74 of the U.S. charts, the band decided to craft a more commercial album. They hired producer Dieter Dierks (famous for his work with the Scorpions) and focused on writing more melodic hard rock. The result was 1985's Metal Heart, a good but unsuccessful album that alienated some of the group's core fans and did not expand its audience. Ironically, Metal Heart is now well-regarded by many Accept fans.
While the band continued on for a few years, Udo left Accept in 1987, effectively ending their period as a premier hard rock band. The band has continued on and off in the intervening years (including a few periods with Udo) and generally continues to have modest success, especially in Europe.
Cool trivia fact: "Midnight Mover" is generally regarded as the first video to use bullet time, which became popularized by The Matrix movies. As with all thing Accept, the use here is completely unsubtle, but cool, although it may cause motion sickness and / or convulsions.