Final answer:
Tonality in music refers to the relationship of pitches, particularly with respect to a central tone called the tonic. The tonic serves as the focal point to which all other pitches and chords are related, giving the music its hierarchical structure and establishing the overall mood and sense of direction.
Step-by-step explanation:
Tonality means that we hear a piece of music in relation to a central tone, which is referred to as the tonic. This concept is fundamental in Western music theory and refers to the hierarchical system in which certain pitches or chords have a central role. The term tonic is often synonymous with the keynote and is the pitch upon which all other pitches of a piece are hierarchically referenced.
The dominant and subdominant are other primary pitches in this hierarchy, but they serve different functions relative to the tonic. The dominant is the fifth scale degree above the tonic, and the subdominant is the fifth scale degree below it (or the fourth scale degree above the tonic). The mediant, another term sometimes confused with tonic, is the third scale degree and has a different role in establishing the tonality of a piece.
Tonality is not only a structural foundation but also an aesthetic one, influencing the mood, direction, and sense of closure in music. It evolved from earlier modal systems in part by the increased use of root motions of fifths, which helped establish a sense of tonal center and direction.