What is Rock?

Rock is a very broad genre of music, has very many different branches, and is very hard to describe verbally. I can't really describe all of rock together but I can break it up into several branches and define it. Well first there is Rock and Roll, which is like Rolling Stones, The Beatles, and Elvis, which is kind of the earlier sound of rock, which usually sounds quite crisp and clean, not really using distortion guitar and there's a lot of focus on singing. Then it moves to Led Zepplin, Black Sabbath, and eventually Metallica which is metal. Metal can be defined by having really loud and fast distortion guitar, as well as loud singing and heavy drum beats. It is usually quite fast and sounds kind of angry sometimes, like in thrash metal. There is also grunge, which can be described as sort of like metal but softer, and it uses non distortion guitar more often. Grunge also often goes off key/making off sounds on purpose to bring out a completely different, sometimes disturbing, emotion. Now there is all other sorts of rock I have not mentioned, and I cant possibly define the broad umbrella of Rock in just a paragraph but I can say that Rock is partly defined by the instruments (mostly guitar, bass, drums, vocals) the attitudes of rebellion (just how the music sounds gives a feeling of fighting or rebelling) and lyrics (which is usually a focus on sex, partying, love, rebelling, and many other things).