Atonality is the musical system that lacks all relation of the tones of a work with a fundamental tone and all the harmonic and functional ties in its melody and chords, without being subject to the rules of tonality.

The opposite system of atonalism should not be called tonalism, but a tonal system.

More specifically, the term describes music that does not conform to the system of tonal hierarchies that characterized the sound of European music between the 17th and early 20th centuries.

Tonal centers gradually replaced the modal organization systems that had developed since the 1500s, culminating in the establishment of the major and minor mode system between the late 16th and mid-17th centuries.

An attentive listener to works particularly from the Baroque, Classical or Romantic periods, or works such as an opera by Antonio Vivaldi, a sonata by Beethoven (1770-1827), is able to notice the ending a few bars before a fragment ends.

The tonal system is the substrate on which almost all composers between 1600 and 1900 were based. In these musical works there is a sound that acts as the center of attraction of the entire work. Although in the course of it the tonal center was changed many times by means of modulations, by convention towards the end the strength of that original nucleus always prevailed and the composition ended when it reached the tonic, that is, the sound of attraction ( in Greek tone means tension).

The basic principle of atonalism is that no sound exerts attraction on any other sound that is in its vicinity. This is why the listener cannot predict even one note before, if it is at the end of a musical phrase (which, apparently, stops at any moment) simply because no tonal center has existed.