This article is about the musical system. For linguistic feature, see Tone (linguistics). For tone colour, see timbre.

Perfect authentic cadence (IV–V–I chord progression, in which we see the chords F Major, G Major, and then C Major, in four-part harmony) in C major About this sound Play (help·info). "Tonal music is built around these tonic and dominant arrival points [cadences], and they form one of the fundamental building blocks of musical structure" (Benjamin, Horvitz, and Nelson 2008, 63).
Tonality is a musical system that arranges pitches or chords to induce a hierarchy of perceived relations, stabilities, and attractions. In this hierarchy, the individual pitch or triadic chord with the greatest stability is called the tonic. The root of the tonic chord is considered to be the key of a piece or song. Thus a piece in which the tonic chord is C major is said to be "in the key of C". Simple folk music songs often start and end with the tonic note. The most common use of the term ..."is to designate the arrangement of musical phenomena around a referential tonic in European music from about 1600 to about 1910" (Hyer 2001). Contemporary classical music from 1910 to the 2000s may practice or avoid any sort of tonality—but harmony in almost all Western popular music remains tonal.[vague] Harmony in jazz music includes many, if not all, tonal characteristics, while having different properties from common practice classical music.

"All harmonic idioms in popular music are tonal, and none is without function" (Tagg 2003, 534).[vague] Tonality is an organized system of tones (e.g., the tones of a major or minor scale) in which one tone (the tonic) becomes the central point for the remaining tones. The other tones in in tonal piece are all defined in terms of their relationship to the tonic. In tonality, the tonic (tonal center) is the tone of complete relaxation and stability, the target toward which other tones lead (Benward & Saker 2003, 36). The cadence (coming to rest point) in which the dominant chord or dominant seventh chord resolves to the tonic chord plays an important role in establishing the tonality of a piece. "Tonal music is music that is unified and dimensional. Music is unified if it is exhaustively referable to a precompositional system generated by a single constructive principle derived from a basic scale-type; it is dimensional if it can nonetheless be distinguished from that precompositional ordering" (Pitt 1995, 299)