Going back to my high school days for this one – just popped into my head yesterday which of course makes it a great entry for today.  I remember hearing this on the radio back in 1979 and immediately loving the simple guitar riff that underlies the rest of the song.  I always thought this was a Rainbow song (although admittedly its the only song by them I know) but the Internet tells me that it was originally done by Russ Ballard in 1976 and subsequently covered by a number of bands before and after Rainbow’s version.