What is referred to as “Western Classical Music” today is the music from the Common Practice Era. In the European music history Common Practice Era spans roughly for three centuries from 1600 to 1910 and includes three major style periods or genres: Baroque (1600-1750), Classical (1750-1830) and Romantic (1815-1910) periods. Common practice period is based on tonal music as oppose to earlier modal music and later atonal music. Earlier music period before the Common Practice Period includes Medieval (500-1400) and Renaissance (1400-1600). Contemporary era is the music period comes after the common practice era.
Principle of the music of the Common Practice Period is based on the major, melodic minor and harmonic minor scales which are many of the scales we use today. Harmony in this period is based on these scale tones and this is the reason why the music of this period is considered to be a tonal music which is a music pleasing to listen to.
Tonal music is a hierarchy of pitches with one pitch as a reference or a focal point which is supported by the other pitches. This primary centre or focal point is called Tonic. The language of Tonal harmony and theory has been developed and structured and commonly used during the common practice period.