Western tonal music is a system of music that is based on a hierarchy of pitches, typically centered around a key. This system uses scales, such as the major and minor scales, to create melodies and harmonies. The relationships between these pitches create a sense of tension and resolution, which is fundamental to the structure of Western music. The development of Western tonal music began in the Middle Ages and evolved through the Renaissance, Baroque, Classical, and Romantic periods. Composers like Bach, Beethoven, and Mozart significantly contributed to this tradition, establishing forms such as the sonata and symphony that are still influential today.