Rock music is a broad category of music typified by songs featuring an energetic drumbeat, usually accompanied by one or more guitars, a bass guitar, and possibly an electronic organ or electric piano. Songs from the rock music genre (particularly pop-rock and pop-punk songs) commonly have 4-4 rhythm structures, although songs from some subgenres (such as metal music songs) have a variety of rhythm structures.
The name derives from the earliest form of the music, rock and roll.