Fundamental musical terms are defined to help all people understand the organized structure of music. Music uses arrangements of sound, melody, harmony, texture, rhythm, and dynamics. Melody is the rhythmic progression of modulated pitches following the time signature. Harmony combines two or more simultaneous music notes, while texture includes monophonic, polyphonic, homophonic, or heterophonic forms. Rhythm can be flowing, random, regular, or progressive, and dynamics show the volume of produced sounds.