Define rock music.[1] Rock music has become so big that it's hard to define it in simple terms. However, most would agree that it is typically guitar-based music with a driving beat and a lot of energy. The definition of rock has changed a great deal over the years. Simply put, the more rock you hear, the better you'll be able to define it for yourself.
What counts as rock and what doesn't can come into question. For instance, the Beatles are generally regarded as the world's most famous rock band, but they're more often referred to as a pop group.