Why is the well tempered Clavier a significant collection?

The Well-Tempered Clavier, composed by Johann Sebastian Bach, is significant for its innovative exploration of tuning and key modulation, showcasing the capabilities of the equal temperament system. It consists of two volumes, each containing 24 preludes and fugues in all major and minor keys, serving as a comprehensive pedagogical tool for keyboard players. This work not only highlights Bach's mastery of counterpoint and harmony but also laid the groundwork for future composers, influencing the development of Western Classical Music. Its enduring popularity and relevance in both performance and teaching further cement its status as a cornerstone of the keyboard repertoire.