In 1941, Walter Piston suggested in his „Harmony“ that the music of the Baroque, the Classical and the Romanticism should be summarized under the term „common practice period“. It is characterized by tonality, that is, the notion of harmony is tied to fixed rules for chords and chord progressions, using defined scales as a musical source material as well as clear, unified rhythms.

The musicologist Leonard Ratner emphasized above all the didactic benefit of this concept:

The idea of a 'common practice' period is valuable in pedagogy since it furnishes the student a standard vocabulary for writing harmonic progressions and for analyzing chords.¹⁾

However, there is also criticism for overemphasizing the tonal and harmonious commonalities of the time, devaluing the variety of music based on them, and failing to duly appreciate the links to the periods before and after.

Having emphasized commonalities, theorists are now coming to a better appreciation (and explanation) of differences. … Backwards compatibility thus makes a case for an overarching common practice of tonality in Western music — which is to say, a common value system about pitch relations before, during, and after the so-called Common-Practice era.²⁾