What Is Classic Rock?

Classic rock is one of the most popular styles of music in the world, touching the lives of generations of people. Yet ironically, no one knows exactly what classic rock is. Led Zeppelin, Jimi Hendrix, Deep Purple: There are certain artists everyone agrees fit the classic rock bill, but where exactly does classic rock begin and where does it end? For some, classic rock constitutes music released during a specific period of time. For others, it's a genre or simply a radio format. As a life long classic rocker, I'm astonished that there's no overall consensus as to the definition of classic rock. Thus, I have taken it upon myself to travel the world, from the Sunset Strip to Abbey Road Studios, interviewing several artists from iconic rock bands in the process, all in search of an answer: How do you define classic rock?