A hard boogie is a song in the hardrock genre which is played with a swing. Hard rock (also referred to as heavy rock) is a variation of Rock music which has its earliest roots in mid-1960s garage and Psychedelic rock Examples are Rock Forever by Judas Priest, Black Night by Deep Purple and Running Free by Iron Maiden. "Rock Forever" is a song by British heavy metal band Judas Priest, originally released on their 1978 album Killing Judas Priest are an English heavy metal band formed in 1970 in Birmingham. " Black Night " is a song by British Hard rock band Deep Purple, first released as a single in June 1970 and later included Deep Purple are an English rock band formed in Hertfordshire in 1968 " Running Free " was the first single released by Iron Maiden. For other uses see Iron maiden.