when my music sensibilities were taking shape "classic rock" was pretty clear cut. Basically, post-Elvis rock, mainly from the 60s and 70s.
But I notice now that some "classic rock" compilations are muddled, and really, what does it mean? Is it "classic" because it's sort of old school and has stood the test of time? (It used to be viewed that way) - or is it classic as a genre / sensibility - in which case something written in 2015 can be "classic rock" - the White Stripes and the Black Keys and others are "classic rock."
I dunno.