This document defines key elements of music including melody, harmony, rhythm, and genre. It explains that melody is an organized succession of pitches that moves between intervals of half steps and whole steps. Harmony involves two or more pitches heard simultaneously. Rhythm refers to the temporal aspects of music including meter and beat. Genre describes a set of musical expectations that can be broad, like classical, or very specific, like a string quartet or hip hop song. The document provides the fundamental building blocks for understanding music.