Rainbow is, to put it shortly, the lovechild of Everything's Better with Rainbows and The Power of Rock. Actually, it is the solo project of former Deep Purple guitarist Ritchie Blackmore. It initially started as a quick off-shoot project of Blackmore (backed by Elf, a Power Trio fronted by Ronnie James Dio) because he wanted to record a cover of Quatermass song "Black Sheep of the Family". After Blackmore left Deep Purple, the band became fulltime project. During the 70's they played Hard Rock but in the early 80's they adopted more AOR-ish sound.