Classic Rock

When did classic rock become classic rock?

What defines classic rock? I grew up in the 1960's and 70's. Primarily, this would be the era in which classic rock originated. The thing is, the term "classic rock" didn't exist then. It was new and on the radio. It wasn't old rock. We just knew it as rock. There were older bands like The Beatles, The Rolling Stones and The Kinks, who all defined rock in the 1960's. Of course, there were versions of rock, like "acid rock", "psychedelic rock", defined by bands like Jefferson Airplane, The Doors, and Strawberry Alarm Clock. In the late 1960's, "theater rock" began with bands like Yes, Genesis, Emerson, Lake and Palmer and King Crimson. This type of rock was considered much more elaborate as they were much longer songs that used indiscriminate odd time signatures and theatrical compositions, which were also used in live shows. Rock as I knew it, were bands like Aerosmith, Boston, Lynyrd Skynyrd, The Who, Led Zeppelin, The Doobie Brothers, Pink Floyd, Jethro Tull, Cream, Bad Company, Bac…